Merge branch 'release/0.5.6' into develop
Revert to basic directory objects for albums/artists

Looks like music models have been broken in the plex framework, maybe this can
be fixed in the future.
Updated spotify.py
Ignore playlists that were unable to be loaded
Updated PyEmitter
Updated spotify.py
Bumped version to 0.5.7
Merge branch 'release/0.5.7'