Synchronizator can disable member using authoritativeGroup attribute

- create new authoritativeGroup attribute module
- change synchronizator code to work with authoritativeGroup attribute

--- NEED TO BE DONE AFTER MERGE THIS COMMIT ---
1] create new attribute authoritativeGroup
2] set rights for this new attribute
 - WRITE = GroupManager, VoManager
 - READ  = VoManager
Merge pull request #374 from stavamichal/synchronizatorCanRemovePeopleFromVo

Synchronizator can disable member using authoritativeGroup attribute