Separation of concerns. 

Move api mapping to the HTTP module and the request actions to RESTActions module.

This PR helps to organize the code and make these two issues separated:

* #35 and #32 


Actually, we need revise this entire module, :).

I made this commit as quick solution, but I think we can plan a way to parse the response in a more proper way. I know we can do this in middlewares, but for example, I have many examples that only includes the root in JSON (like many Rails APIs).

I would like discuss this in the #32. This parte needs a little remodeling and planning the flows and the objects itself. For example, i think all resources should have a last_response accessor that returns the last requested data. I need to think more about many things in that area, :)