s4sync fixes
Several fixes to improve s4sync, specially when zarafa and mail installed
Return OUs hierarquically ordered
Improve LDAP OUs purge after joining
Fix indentation
Import only used function
Merge branch '3.2' into scabrero/samba-fix-s4sync

Conflicts:
	main/samba/ChangeLog
	main/users/ChangeLog
Add migration code
Merge pull request #799 from Zentyal/scabrero/samba-fix-s4sync

s4sync fixes