Enhance the VocabularyRestlet

The Nuxeo VocabularyRestlet could be enhanced to allow hierarchical simple export.
The existing Nuxeo one is suitable for exporting the directories, just that it requires more complex computations on client. The Nuxeo's default restlet exports the directories maintaining the relations between parent and child directories inside, whilst here a pure import (replace) is done. In future, the usage of this dedicated restlet could be dropped favoring the Nuxeo pure one. It only need exporting the "obsolete" field too and maybe (based on a parameter) to follow a simpler export scheme.