feat($http): Pass http config to response interceptors

Allow response interceptors to use the config object passed to the
$http call that the response originated from

-------

This arose from a use case where I needed a global loading indicator with loading messages that were customized for each endpoint.

Here is a jsfiddle I created that demonstrates this use case with a build of angular including this change: http://jsfiddle.net/ashelvey/UJ2Xx/ 

You can use Charles, Fiddler, etc.. to throttle http calls for a more realistic demo.

(CLA signed)