Enhancements:
- Cancel subscriptions on exit (see #5).
Bug fixex:
- After a zone leaves a group, and the now standalone has no music source selected:
- The group for the now standalone zone would show On (play/pause) as true;
- The group for the now standalone zone would continue to show the track the old group was playing when the zone left the group.
Bump dependencies:
- homebridge v0.4.44;
- homebridge-lib v1.0.5.