* LockScreenAudio.csproj: Added ReadMe.md to project

* MusicQuery.cs: Added song duration to information retrieved from the
  media query.

* MyMusicPlayer.cs: Added seeking functionality from lock and control
  screen with long press of forward and back buttons. Also current
  media item will pause at end rather than unload itself. This was so
  when there was only one song you could still go back to the
  beginning and play it again, but this interrupts playback when there
  is another song in the Queue. 

* Song.cs: Added duration to Song class.