Use response method for track_info handler

mycroft/audio/audioservice.py

@@ -484,8 +484,7 @@ def _track_info(self, message):
             track_info = self.current.track_info()
         else:
             track_info = {}
-        self.bus.emit(Message('mycroft.audio.service.track_info_reply',
-                              data=track_info))
+        self.bus.emit(message.response(track_info))
 
     def _list_backends(self, message):
         """ Return a dict of available backends. """

mycroft/skills/audioservice.py

@@ -148,7 +148,6 @@ def track_info(self):
         """
         info = self.bus.wait_for_response(
             Message('mycroft.audio.service.track_info'),
-            reply_type='mycroft.audio.service.track_info_reply',
             timeout=1)
         return info.data if info else {}