Univention Corporate Server 3.2 erratum 170 (bugfix)

This update fixes several issues:
* Removing all Nagios services from a computer object no longer yields an
  error.
* Same for Nagios hosts.
* Adding a DNS reverse zone to a computer object while removing an IP address
  no longer yields an error as well.
* Documentation for a UCR variable added that makes the name of an object in
  the frontend grid configurable.
* Removed the input field Organisation from the group Personal information 
  and added it to the group Organisation.
* Added new option to share-userquota policy: Reapply quota on every login
* Add possibility to mark UDM properties as readonly when UCS is part of an
  Active Directory domain.
* The script "proof_uniqueMembers" will no more crash on empty uniqueMember
  attributes.