Use voluptuous for Raspberry Pi and local file camera (#2988)

* Migrate to voluptuous

* Update const.py

* Migrate to voluptuous

* Remove duplicate _LOGGER entry

homeassistant/components/camera/local_file.py

@@ -1,5 +1,9 @@
-"""Camera that loads a picture from a local file."""
+"""
+Camera that loads a picture from a local file.
 
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/camera.local_file/
+"""
 import logging
 import os
 
@@ -9,7 +13,10 @@ from homeassistant.const import CONF_NAME
 from homeassistant.components.camera import Camera, PLATFORM_SCHEMA
 from homeassistant.helpers import config_validation as cv
 
+_LOGGER = logging.getLogger(__name__)
+
 CONF_FILE_PATH = 'file_path'
+
 DEFAULT_NAME = 'Local File'
 
 PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
@@ -17,8 +24,6 @@ PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
     vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string
 })
 
-_LOGGER = logging.getLogger(__name__)
-
 
 def setup_platform(hass, config, add_devices, discovery_info=None):
     """Setup the Camera."""