Implemented Full Response Interceptor

When working with Restangular, especially list based services, I often have the need of manipulating and extending collections with information that is only available via the request headers. Restangular does not make this very convenient or easy. The only clean way that I found to do it was with the fullResponse option but that requires more external handling than is really necessary. To solve this problem, I implemented a simple hook that I've named "full response interceptor" based on the full request interceptor idea. The full response interceptor gives you access to the fully restangularized data, the complete $http response object, as well as the promise object.