Refactored, using Rails responder API

I changed the API controller into a more Rails Way implementation using respond_with method. Internally it knows what to respond with the format you pass on the URL. So I had to change all the paths in the angular services to use the .json format.

Also I changed the destroy_many route to use delete HTTP method as it is the standard RESTful API as you are destroying resources.

I liked the concept behind angular_sprinkles, and I think, with this merge, it is simpler as you have to maintain less code, and you take advantage of the Rails potential. 

Tell me what do you think!