First pass adding android auto and apple carplay support. Android auto tuned on emulator.

lib/streaming_audio_business_object.dart

@@ -101,6 +101,7 @@ class StreamingAudioBusinessObject extends ChangeNotifier {
 
   Future<void> stop() async {
     _playRequested = false;
+    _isSourceLoaded = false;
     _setPlaybackStatus(StreamingPlaybackStatus.stopped);
     await _player.stop();
   }