context optional and year to string.

[evanscottgray]

context should be optional because you can end up with a url that looks like my.subsonic.server/False/rest or my.subsonic.server/''/rest and mopidy itself will complain if you don't set it since it is not optional currently.

I suppose this is a duplicate of #19 but I think offering it as an option feels nice in general.

then a fix to client to force data['year'] to a string which is basically #18.

this also addresses #14, #15

[ronihcohen]

Hey @evanscottgray, did this fix work for you? I am still getting the following err:

2016-08-20 20:06:00,015 ERROR [3011:MainThread] mopidy.commands: Got un-handled exception from SubsonicBackend
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/mopidy/commands.py", line 237, in _actor_error_handling
    yield
  File "/usr/lib/python2.7/dist-packages/mopidy/commands.py", line 385, in start_backends
    config=config, audio=audio).proxy()
  File "/usr/lib/python2.7/dist-packages/pykka/actor.py", line 94, in start
    obj = cls(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/mopidy_subsonic/actor.py", line 32, in __init__
    self.playlists = SubsonicPlaylistsProvider(backend=self)
  File "/usr/local/lib/python2.7/dist-packages/mopidy_subsonic/playlist.py", line 15, in __init__
    self.playlists = self._get_playlists()
  File "/usr/local/lib/python2.7/dist-packages/mopidy_subsonic/playlist.py", line 36, in _get_playlists
    playlists = self.remote.get_user_playlists()
  File "/usr/local/lib/python2.7/dist-packages/mopidy_subsonic/client.py", line 364, in get_user_playlists
    for playlist in results]