Code review comment for lp:~victored/beat-box/equalizer-fixes

I am merging the changes, however:

1. In lm.change_gains_thread, errors are thrown when no song is playing (i.e. song_info.song == null).
2. ... that's it!

So, what i'm going to do is merge and then I will add a simple check for that myself, since it's easier that way.

Great work again!