Previous exchange feedbacks:
* renamed some fields
* added would recommend field in course feedback
* uniformized grading scheme
* Added viewsets/serializers in the back (+permissions & performance concerns)
* Support edit in the front

Tweaks:
* directly return in the `obj_info` if the model is versioned or not
* Added support for required get parameters
* enum for model moderation level
* More versatile metric feedback component
* Fixed how the editor (frontend component) was telling if something has been moderated
* Added a CURRENT_USER variable instead of using the one from html directly
* Diminished website font-size
* Better proptypes / defaultProps in fields
* Added optionnal comment text on fields
* Fixed the number field
* Added Helper classes to centralize the manipulation of redux store data
* Teaked pseudo/username returned by the api

Closes #29 #32