Fixed the tests
Refactoring render to json and ajax js

* render_to_json
- removed the success var
- added status text and path of the request in all responses
- added support for more http response (django 1.6)
- added support for Http404

* ajax js
- removed the success var
- added support for fail request and redirect response
- added the message of the fail request
- onsuccess is fired if the status code is equal to 200
Fixed documentation
Fixed the version
Updated the travis tester