LPS-22792 Encapsulate logic from AssetVocabulary Settings in a helper object

Hey Brian, 

the biggest benefit of having this logic in a separated class is that we can have UNIT tests. Otherwise, if we move that to the model, we need to use integration tests. 

We have renamed to make clearer what it is. It is mainly a model helper to handle all the logic about the settings, but it is internal and its only goal is to encapsulate all this logic in a single place and make it easy to test.

I can jump into skype if you want to talk about it.

thanks!