Issue #61: More features than you can shake a stick at.

* Implemented seekbar listener
* Implemented Pause, Skip Forward, Skip Back
* Implemented Music Library preference
* Implemented Play All from selected track.
* Improved spacing of on screen controls.
Issue #61: Add KeyBoard and Remote response codes for Music playback.
Issue #97: Add ability to select default subtitle

This adds the ability to select the default subititle based on the
available locales.  Users need to enable the functionality in the preferences
and also select their default language.   If a subtitle matches the
two character code, it will be selected automatically.  This only works for
external subtitles.