quickly when the app is in the background and *not* playing music. This
had the effect of breaking all player actions within the app (queue
listing, playback control, etc.).
This "starts" PlayerService every time MainActivity is resumed, which is
a noop if the service is still running, but allows retrieving app
functionality otherwise.
Better handling of startup (login activity would reset if put in the background).
Allow use of schemeless hostname for login.
Destroy main activity and clear cache on logout.
Change of endpoint for favorites retrieval for one with much better performance.