GROSS COMMIT: Added composition post method, added composition createFromJson

Really just trying to synch up.
Pulled from origin, fixed conflicts
Merge branch 'models' of https://github.com/clausman/soco into models
Merge branch 'models' of https://github.com/clausman/soco into models
Merge branch 'models' of https://github.com/clausman/soco into models
Added post methods to api for Compositions and Tracks. Added createFromObject to Composition and Tracks
Merge changes