* Add mysensors device_tracker platform
* Add discovery of device_tracker platforms
* Enable discovery of device_tracker platforms that are not
DeviceScanner.
* Update signature of setup_scanner function in all affected platforms.
* Add test.
* Use discovery for mysensors device_tracker platform.
* Remove gps accuracy
* Small change to core like schema
* fix depency
This tracker discovers new devices on boot and tracks bluetooth devices
periodically based on interval_seconds value. Devices discovered are
stored with 'BT_' as the prefix for device mac.
Requires PyBluez