Description of problem:
When I click on the pause button in the Music Applet while running Exaile it
goes to the next song instead of pausing.  When hitting play it does the same thing.

Steps to Reproduce:
1. Start Exaile from clicking on Music Applet with Exaile plugin
2. Start playing song from within Exaile
3. Try pausing using the applet.
4. Pause from inside Exaile and try using applet to start.
  
Actual results:
For pausing the applet moves to next song instead.
For playing it starts but skips to next song as well.

Expected results:
Pause should pause the song.
Play should start up the song without changing songs.