Playback and indexing now occur in the same service through a new
bridge called AuxioService.
AuxioService contains the existing service instances as Fragment
implementations, and then forwards typical service events to them
(albeit this will drift more and more as I continue to deal with
lifecycle issues).
This should be the first step in enabling true service independence,
as it means that the service will now immediately initialize and load
music as soon as possible.
