Univention Corporate Server 4.0 erratum 261 (bugfix)

This update addresses the following issue:
* An API change introduced in erratum 217 and a UDM module move in
  erratum 236 led to UDM/UMC problems on UCS systems with an UCS
  version prior to 4.0-2 errata level 217.
  The UDM module policies/mailquota is now able to use the old and
  the new API.