Rewrite for 2.0 with much better code base.

- Improvements on AppMessages and memory usage.
- Add ground base to easily add option to customize what each button does either on Pebble or via the configuration page.
- Add initial Plex Pass support.
- Other small improvements like opening last used player automatically on launch.
Fix #6 by not hard coding playerid and request it from server on launch.
Make windows only update if they're loaded. Other small stuff.
Add X-Plex-Token for when the server enforces local network authentication.
Merge branch 'dev'

* dev:
  Add X-Plex-Token for when the server enforces local network authentication.
  Make windows only update if they're loaded. Other small stuff.
  Fix #6 by not hard coding playerid and request it from server on launch.
  Rewrite for 2.0 with much better code base.