I do this by creating a new Listen class that is constructed from one of
our db.track.Tracks to convert to something liblistenbrainz understands.
From there, I watch for changes to the "now-playing" property and call
out to the Thread to submit the track to ListenBrainz.
Implements: #69 ("Add ListenBrainz support")
Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>