Add support for additional services: (Google Music and/or Pandora)

[cvanderschuere]

Integrate another service into the current device model to help with abstraction:

Current work:

• Pandora
• VLC

Todo:

• Bugs in go-vlc that prevent constant playback
• Figure out delay issues with google music api (Not practical with them)

[cvanderschuere]

More work on Google Music to follow