Cleanup; added empty Player activity
Rebuild sample library in background/on request
Player plays a single, hard-coded track

Playback stops when the activity exits
Media player now runs in a service.

Progress bar disabled for the moment.
Progress bar follows track; can seek
Run the player as a foreground service

- Foreground notification opens the player activity without duplicating
  it
- Hard-coded tracks come in a list from the library
- Progress bar stops updating if the player isn't foregrounded
Music player is launched from the library

- missing track sends a warning from player service, doesn't open player
  activity
Player activity controls its service by binding.

Service doesn't broadcast normal state updates.
Player error broadcasts send the original status codes.
Player's notification is built in onCreate
Player stops if it loses audio focus
Player is paused when headphones are unplugged
Fix & clean up player event broadcasts
Cleaned up broadcasts on play.
Merge pull request #7 from patrick-conley/play-a-single-track

Play a single track