Add support for Prowl notifications. (#9028)

* Add support for Prowl notifications.

* Use HA session handler.

* Simplify http request logic.

* flake

* fix double fetch data

* Remove periods from log messages

.coveragerc

@@ -399,6 +399,7 @@ omit =
     homeassistant/components/notify/message_bird.py
     homeassistant/components/notify/nfandroidtv.py
     homeassistant/components/notify/nma.py
+    homeassistant/components/notify/prowl.py
     homeassistant/components/notify/pushbullet.py
     homeassistant/components/notify/pushetta.py
     homeassistant/components/notify/pushover.py

homeassistant/components/notify/prowl.py

@@ -0,0 +1,70 @@
+"""
+Prowl notification service.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/notify.prowl/
+"""
+import logging
+import asyncio
+
+import async_timeout
+import voluptuous as vol
+
+from homeassistant.components.notify import (
+    ATTR_TITLE, ATTR_TITLE_DEFAULT, ATTR_DATA, PLATFORM_SCHEMA,
+    BaseNotificationService)
+from homeassistant.const import CONF_API_KEY
+import homeassistant.helpers.config_validation as cv
+from homeassistant.helpers.aiohttp_client import async_get_clientsession
+
+_LOGGER = logging.getLogger(__name__)
+_RESOURCE = 'https://api.prowlapp.com/publicapi/'
+
+PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
+    vol.Required(CONF_API_KEY): cv.string,
+})
+
+
+@asyncio.coroutine
+def async_get_service(hass, config, discovery_info=None):
+    """Get the Prowl notification service."""
+    return ProwlNotificationService(hass, config[CONF_API_KEY])
+
+
+class ProwlNotificationService(BaseNotificationService):
+    """Implement the notification service for Prowl."""
+
+    def __init__(self, hass, api_key):
+        """Initialize the service."""
+        self._hass = hass
+        self._api_key = api_key
+
+    @asyncio.coroutine
+    def async_send_message(self, message, **kwargs):
+        """Send the message to the user."""
+        response = None
+        session = None
+        url = '{}{}'.format(_RESOURCE, 'add')
+        data = kwargs.get(ATTR_DATA)
+        payload = {
+            'apikey': self._api_key,
+            'application': 'Home-Assistant',
+            'event': kwargs.get(ATTR_TITLE, ATTR_TITLE_DEFAULT),
+            'description': message,
+            'priority': data['priority'] if data and 'priority' in data else 0
+        }
+
+        _LOGGER.debug("Attempting call Prowl service at %s", url)
+        session = async_get_clientsession(self._hass)
+
+        try:
+            with async_timeout.timeout(10, loop=self._hass.loop):
+                response = yield from session.post(url, data=payload)
+                result = yield from response.text()
+
+            if response.status != 200 or 'error' in result:
+                _LOGGER.error("Prowl service returned http "
+                              "status %d, response %s",
+                              response.status, result)
+        except asyncio.TimeoutError:
+            _LOGGER.error("Timeout accessing Prowl at %s", url)