Extended API to support ratings
Added the following calls:
 - POST songs/{id}/rate
 - POST movies/{id}/rate
 - GET songs/{id}/ratings?userId={userId}
 - GET movies/{id}/ratings?userId={userId}
Extended movie and songs return types (wrappers) with the following fields:
 - avgRating
 - numberOfVotes
Merge branch 'master' of github.com:Bladtman242/ITU.Year2.RentIt