[IMP] Improvement/changes to the http request/response API.

[IMP] Improvement/changes to the http request/response API.

- Added http.Response object
- @http.route decorator wraps methods in order to convert returned value to Response object
- http.Request.func* variables moved to http.EndPoint class
- moved _first_arg_is_req backward compatibility feature in EndPoint class
- CORS support moved to new http.Request object
- Added a #render() helper on request object as a companion of #make_response() that will return a lazy qweb rendering response
- Extra check in routing_map() in order to forbid the chabge of request type in @http.route arguments inheritance
- Fix crash happening when no Host header is present in the request

bzr revid: fme@openerp.com-20140226164407-5avn72p20o3o4f7x