diff --git a/homeassistant/const.py b/homeassistant/const.py
index 4bf1785fe7b..e2e76d8b86e 100644
--- a/homeassistant/const.py
+++ b/homeassistant/const.py
@@ -1,7 +1,7 @@
 # coding: utf-8
 """Constants used by Home Assistant components."""
 
-__version__ = "0.27.0.dev0"
+__version__ = '0.27.0.dev0'
 REQUIRED_PYTHON_VER = (3, 4)
 
 PLATFORM_FORMAT = '{}.{}'
@@ -10,7 +10,7 @@ PLATFORM_FORMAT = '{}.{}'
 MATCH_ALL = '*'
 
 # If no name is specified
-DEVICE_DEFAULT_NAME = "Unnamed Device"
+DEVICE_DEFAULT_NAME = 'Unnamed Device'
 
 WEEKDAYS = ['mon', 'tue', 'wed', 'thu', 'fri', 'sat', 'sun']
 
@@ -74,15 +74,15 @@ CONF_WHITELIST = 'whitelist'
 CONF_ZONE = 'zone'
 
 # #### EVENTS ####
-EVENT_HOMEASSISTANT_START = "homeassistant_start"
-EVENT_HOMEASSISTANT_STOP = "homeassistant_stop"
-EVENT_STATE_CHANGED = "state_changed"
-EVENT_TIME_CHANGED = "time_changed"
-EVENT_CALL_SERVICE = "call_service"
-EVENT_SERVICE_EXECUTED = "service_executed"
-EVENT_PLATFORM_DISCOVERED = "platform_discovered"
-EVENT_COMPONENT_LOADED = "component_loaded"
-EVENT_SERVICE_REGISTERED = "service_registered"
+EVENT_HOMEASSISTANT_START = 'homeassistant_start'
+EVENT_HOMEASSISTANT_STOP = 'homeassistant_stop'
+EVENT_STATE_CHANGED = 'state_changed'
+EVENT_TIME_CHANGED = 'time_changed'
+EVENT_CALL_SERVICE = 'call_service'
+EVENT_SERVICE_EXECUTED = 'service_executed'
+EVENT_PLATFORM_DISCOVERED = 'platform_discovered'
+EVENT_COMPONENT_LOADED = 'component_loaded'
+EVENT_SERVICE_REGISTERED = 'service_registered'
 
 # #### STATES ####
 STATE_ON = 'on'
@@ -107,94 +107,94 @@ STATE_UNAVAILABLE = 'unavailable'
 
 # #### STATE AND EVENT ATTRIBUTES ####
 # Contains current time for a TIME_CHANGED event
-ATTR_NOW = "now"
+ATTR_NOW = 'now'
 
 # Contains domain, service for a SERVICE_CALL event
-ATTR_DOMAIN = "domain"
-ATTR_SERVICE = "service"
-ATTR_SERVICE_DATA = "service_data"
+ATTR_DOMAIN = 'domain'
+ATTR_SERVICE = 'service'
+ATTR_SERVICE_DATA = 'service_data'
 
 # Data for a SERVICE_EXECUTED event
-ATTR_SERVICE_CALL_ID = "service_call_id"
+ATTR_SERVICE_CALL_ID = 'service_call_id'
 
 # Contains one string or a list of strings, each being an entity id
 ATTR_ENTITY_ID = 'entity_id'
 
 # String with a friendly name for the entity
-ATTR_FRIENDLY_NAME = "friendly_name"
+ATTR_FRIENDLY_NAME = 'friendly_name'
 
 # A picture to represent entity
-ATTR_ENTITY_PICTURE = "entity_picture"
+ATTR_ENTITY_PICTURE = 'entity_picture'
 
 # Icon to use in the frontend
-ATTR_ICON = "icon"
+ATTR_ICON = 'icon'
 
 # The unit of measurement if applicable
-ATTR_UNIT_OF_MEASUREMENT = "unit_of_measurement"
+ATTR_UNIT_OF_MEASUREMENT = 'unit_of_measurement'
 
 CONF_UNIT_SYSTEM_METRIC = 'metric'  # type: str
 CONF_UNIT_SYSTEM_IMPERIAL = 'imperial'  # type: str
 
 # Temperature attribute
-ATTR_TEMPERATURE = "temperature"
-TEMP_CELSIUS = "°C"
-TEMP_FAHRENHEIT = "°F"
+ATTR_TEMPERATURE = 'temperature'
+TEMP_CELSIUS = '°C'
+TEMP_FAHRENHEIT = '°F'
 
 # Length units
-LENGTH_CENTIMETERS = "cm"  # type: str
-LENGTH_METERS = "m"  # type: str
-LENGTH_KILOMETERS = "km"  # type: str
+LENGTH_CENTIMETERS = 'cm'  # type: str
+LENGTH_METERS = 'm'  # type: str
+LENGTH_KILOMETERS = 'km'  # type: str
 
-LENGTH_INCHES = "in"  # type: str
-LENGTH_FEET = "ft"  # type: str
-LENGTH_YARD = "yd"  # type: str
-LENGTH_MILES = "mi"  # type: str
+LENGTH_INCHES = 'in'  # type: str
+LENGTH_FEET = 'ft'  # type: str
+LENGTH_YARD = 'yd'  # type: str
+LENGTH_MILES = 'mi'  # type: str
 
 # Volume units
-VOLUME_LITERS = "L"  # type: str
-VOLUME_MILLILITERS = "mL"  # type: str
+VOLUME_LITERS = 'L'  # type: str
+VOLUME_MILLILITERS = 'mL'  # type: str
 
-VOLUME_GALLONS = "gal"  # type: str
-VOLUME_FLUID_OUNCE = "fl. oz."  # type: str
+VOLUME_GALLONS = 'gal'  # type: str
+VOLUME_FLUID_OUNCE = 'fl. oz.'  # type: str
 
 # Mass units
-MASS_GRAMS = "g"  # type: str
-MASS_KILOGRAMS = "kg"  # type: str
+MASS_GRAMS = 'g'  # type: str
+MASS_KILOGRAMS = 'kg'  # type: str
 
-MASS_OUNCES = "oz"  # type: str
-MASS_POUNDS = "lb"  # type: str
+MASS_OUNCES = 'oz'  # type: str
+MASS_POUNDS = 'lb'  # type: str
 
 # Contains the information that is discovered
-ATTR_DISCOVERED = "discovered"
+ATTR_DISCOVERED = 'discovered'
 
 # Location of the device/sensor
-ATTR_LOCATION = "location"
+ATTR_LOCATION = 'location'
 
-ATTR_BATTERY_LEVEL = "battery_level"
+ATTR_BATTERY_LEVEL = 'battery_level'
 
 # For devices which support a code attribute
 ATTR_CODE = 'code'
 ATTR_CODE_FORMAT = 'code_format'
 
 # For devices which support an armed state
-ATTR_ARMED = "device_armed"
+ATTR_ARMED = 'device_armed'
 
 # For devices which support a locked state
-ATTR_LOCKED = "locked"
+ATTR_LOCKED = 'locked'
 
 # For sensors that support 'tripping', eg. motion and door sensors
-ATTR_TRIPPED = "device_tripped"
+ATTR_TRIPPED = 'device_tripped'
 
 # For sensors that support 'tripping' this holds the most recent
 # time the device was tripped
-ATTR_LAST_TRIP_TIME = "last_tripped_time"
+ATTR_LAST_TRIP_TIME = 'last_tripped_time'
 
 # For all entity's, this hold whether or not it should be hidden
-ATTR_HIDDEN = "hidden"
+ATTR_HIDDEN = 'hidden'
 
 # Location of the entity
-ATTR_LATITUDE = "latitude"
-ATTR_LONGITUDE = "longitude"
+ATTR_LATITUDE = 'latitude'
+ATTR_LONGITUDE = 'longitude'
 
 # Accuracy of location in meters
 ATTR_GPS_ACCURACY = 'gps_accuracy'
@@ -203,35 +203,35 @@ ATTR_GPS_ACCURACY = 'gps_accuracy'
 ATTR_ASSUMED_STATE = 'assumed_state'
 
 # #### SERVICES ####
-SERVICE_HOMEASSISTANT_STOP = "stop"
-SERVICE_HOMEASSISTANT_RESTART = "restart"
+SERVICE_HOMEASSISTANT_STOP = 'stop'
+SERVICE_HOMEASSISTANT_RESTART = 'restart'
 
 SERVICE_TURN_ON = 'turn_on'
 SERVICE_TURN_OFF = 'turn_off'
 SERVICE_TOGGLE = 'toggle'
 
-SERVICE_VOLUME_UP = "volume_up"
-SERVICE_VOLUME_DOWN = "volume_down"
-SERVICE_VOLUME_MUTE = "volume_mute"
-SERVICE_VOLUME_SET = "volume_set"
-SERVICE_MEDIA_PLAY_PAUSE = "media_play_pause"
-SERVICE_MEDIA_PLAY = "media_play"
-SERVICE_MEDIA_PAUSE = "media_pause"
-SERVICE_MEDIA_STOP = "media_stop"
-SERVICE_MEDIA_NEXT_TRACK = "media_next_track"
-SERVICE_MEDIA_PREVIOUS_TRACK = "media_previous_track"
-SERVICE_MEDIA_SEEK = "media_seek"
+SERVICE_VOLUME_UP = 'volume_up'
+SERVICE_VOLUME_DOWN = 'volume_down'
+SERVICE_VOLUME_MUTE = 'volume_mute'
+SERVICE_VOLUME_SET = 'volume_set'
+SERVICE_MEDIA_PLAY_PAUSE = 'media_play_pause'
+SERVICE_MEDIA_PLAY = 'media_play'
+SERVICE_MEDIA_PAUSE = 'media_pause'
+SERVICE_MEDIA_STOP = 'media_stop'
+SERVICE_MEDIA_NEXT_TRACK = 'media_next_track'
+SERVICE_MEDIA_PREVIOUS_TRACK = 'media_previous_track'
+SERVICE_MEDIA_SEEK = 'media_seek'
 
-SERVICE_ALARM_DISARM = "alarm_disarm"
-SERVICE_ALARM_ARM_HOME = "alarm_arm_home"
-SERVICE_ALARM_ARM_AWAY = "alarm_arm_away"
-SERVICE_ALARM_TRIGGER = "alarm_trigger"
+SERVICE_ALARM_DISARM = 'alarm_disarm'
+SERVICE_ALARM_ARM_HOME = 'alarm_arm_home'
+SERVICE_ALARM_ARM_AWAY = 'alarm_arm_away'
+SERVICE_ALARM_TRIGGER = 'alarm_trigger'
 
-SERVICE_LOCK = "lock"
-SERVICE_UNLOCK = "unlock"
+SERVICE_LOCK = 'lock'
+SERVICE_UNLOCK = 'unlock'
 
-SERVICE_OPEN = "open"
-SERVICE_CLOSE = "close"
+SERVICE_OPEN = 'open'
+SERVICE_CLOSE = 'close'
 
 SERVICE_MOVE_UP = 'move_up'
 SERVICE_MOVE_DOWN = 'move_down'
@@ -241,22 +241,22 @@ SERVICE_STOP = 'stop'
 # #### API / REMOTE ####
 SERVER_PORT = 8123
 
-URL_ROOT = "/"
-URL_API = "/api/"
-URL_API_STREAM = "/api/stream"
-URL_API_CONFIG = "/api/config"
-URL_API_DISCOVERY_INFO = "/api/discovery_info"
-URL_API_STATES = "/api/states"
-URL_API_STATES_ENTITY = "/api/states/{}"
-URL_API_EVENTS = "/api/events"
-URL_API_EVENTS_EVENT = "/api/events/{}"
-URL_API_SERVICES = "/api/services"
-URL_API_SERVICES_SERVICE = "/api/services/{}/{}"
-URL_API_EVENT_FORWARD = "/api/event_forwarding"
-URL_API_COMPONENTS = "/api/components"
-URL_API_ERROR_LOG = "/api/error_log"
-URL_API_LOG_OUT = "/api/log_out"
-URL_API_TEMPLATE = "/api/template"
+URL_ROOT = '/'
+URL_API = '/api/'
+URL_API_STREAM = '/api/stream'
+URL_API_CONFIG = '/api/config'
+URL_API_DISCOVERY_INFO = '/api/discovery_info'
+URL_API_STATES = '/api/states'
+URL_API_STATES_ENTITY = '/api/states/{}'
+URL_API_EVENTS = '/api/events'
+URL_API_EVENTS_EVENT = '/api/events/{}'
+URL_API_SERVICES = '/api/services'
+URL_API_SERVICES_SERVICE = '/api/services/{}/{}'
+URL_API_EVENT_FORWARD = '/api/event_forwarding'
+URL_API_COMPONENTS = '/api/components'
+URL_API_ERROR_LOG = '/api/error_log'
+URL_API_LOG_OUT = '/api/log_out'
+URL_API_TEMPLATE = '/api/template'
 
 HTTP_OK = 200
 HTTP_CREATED = 201
@@ -268,25 +268,25 @@ HTTP_METHOD_NOT_ALLOWED = 405
 HTTP_UNPROCESSABLE_ENTITY = 422
 HTTP_INTERNAL_SERVER_ERROR = 500
 
-HTTP_HEADER_HA_AUTH = "X-HA-access"
-HTTP_HEADER_ACCEPT_ENCODING = "Accept-Encoding"
-HTTP_HEADER_CONTENT_TYPE = "Content-type"
-HTTP_HEADER_CONTENT_ENCODING = "Content-Encoding"
-HTTP_HEADER_VARY = "Vary"
-HTTP_HEADER_CONTENT_LENGTH = "Content-Length"
-HTTP_HEADER_CACHE_CONTROL = "Cache-Control"
-HTTP_HEADER_EXPIRES = "Expires"
-HTTP_HEADER_ORIGIN = "Origin"
-HTTP_HEADER_X_REQUESTED_WITH = "X-Requested-With"
-HTTP_HEADER_ACCEPT = "Accept"
-HTTP_HEADER_ACCESS_CONTROL_ALLOW_ORIGIN = "Access-Control-Allow-Origin"
-HTTP_HEADER_ACCESS_CONTROL_ALLOW_HEADERS = "Access-Control-Allow-Headers"
+HTTP_HEADER_HA_AUTH = 'X-HA-access'
+HTTP_HEADER_ACCEPT_ENCODING = 'Accept-Encoding'
+HTTP_HEADER_CONTENT_TYPE = 'Content-type'
+HTTP_HEADER_CONTENT_ENCODING = 'Content-Encoding'
+HTTP_HEADER_VARY = 'Vary'
+HTTP_HEADER_CONTENT_LENGTH = 'Content-Length'
+HTTP_HEADER_CACHE_CONTROL = 'Cache-Control'
+HTTP_HEADER_EXPIRES = 'Expires'
+HTTP_HEADER_ORIGIN = 'Origin'
+HTTP_HEADER_X_REQUESTED_WITH = 'X-Requested-With'
+HTTP_HEADER_ACCEPT = 'Accept'
+HTTP_HEADER_ACCESS_CONTROL_ALLOW_ORIGIN = 'Access-Control-Allow-Origin'
+HTTP_HEADER_ACCESS_CONTROL_ALLOW_HEADERS = 'Access-Control-Allow-Headers'
 
 ALLOWED_CORS_HEADERS = [HTTP_HEADER_ORIGIN, HTTP_HEADER_ACCEPT,
                         HTTP_HEADER_X_REQUESTED_WITH, HTTP_HEADER_CONTENT_TYPE,
                         HTTP_HEADER_HA_AUTH]
 
-CONTENT_TYPE_JSON = "application/json"
+CONTENT_TYPE_JSON = 'application/json'
 CONTENT_TYPE_MULTIPART = 'multipart/x-mixed-replace; boundary={}'
 CONTENT_TYPE_TEXT_PLAIN = 'text/plain'