Fixed collection class hierarchy

We don't need to distinguish between collection members pointing to a concept and members pointing to a collection. We look at the target instead.

This isn't already done. The editing of collections doesn't work yet.
Merge branch 'master' of github.com:innoq/iqvoc
Fixed whitespace
Merge branch 'master' of github.com:innoq/iqvoc into fix_collections
Never show empty labels in entity select data
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
fixed typos in method names and vars
Merge pull request #189 from innoq/fix_collections

rebuild collections