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.