* Move more constants to const.py
* Import constants directly from const
* ATTR_ENTITY_ID is not defined in media_player
* MEDIA_PLAYER_PLAY_MEDIA_SCHEMA is still in __init__.py
* Correct imports in tts
* PLATFORM_SCHEMA, SCHEMA is still defined in __init__.py
* Pandora imports several services
* Some additional fixes for move of const in media_player
* Fix hound lengths
* New media_player platform for Russound devices using the RIO protocol
Auto discovers zones and sources
Handles media metadata from sources that support it
asyncio implementation
Push updates for any zone or source changes so no polling required.
* Fixed up linting issues
* Addressing PR feedback
Updated russound_rio dependency to 0.1.3
Use enumerate_zones and enumerate_sources methods instead of doing it in
the platform.
Register callbacks in async_added_to_hass coroutine
Corrected behavior of async methods
