I cleaned up the CORSHandler code a bit more and also rewrote the
helper to use the framework to access the request properly and
took care of also grabbing the request schema from the server.
This fixes CORS to work properly with most 2.5 api endpoints while keeping the JSONP format available.
* [x] return JSONP or JSON with proper CORS headers from API
* [x] Field in Genereal Preferences Form to configure CORS enabled URLs
See #17 for what triggered this refactor. I beleive this should make integrating the APIs on the client side trivial without mandating the use of JSONP.