Rebuild `regenereate_members`

This methods are used to rewrite the `.members` relation content by an array of {concept|collection}origins
Fixed naming

It if is a Labeling we should call it a 'labeling'
Fixed confusing success message

The message is used for creation and update
Completed Collection model restructuring

We don't need an array of member classes anymore because there is only one
Rebuild /collections

* There is no hierarchical_concepts_controller anymore
* Fixed some eager loading