Ideally, I think that ```get_music_library_information``` should return an iterable. I have in mind being able to do something like this:

```python
artists = soco.get_library_information(self, "artists", 1, 100)
for artist in artists:
    print artist.name
print "there are {} artists in total".format(artists.total_matches)"
print "the update id is {}".format(artists.update_id)"
```

Having to use ```artists['item_list']``` looks really ugly to me!