Univention Corporate Server 4.4 erratum 306 (bugfix)

This update addresses the following issues:
* The logging and error handling when removing child objects
  has been improved.
* The DHCP assignment for computers with mutliple MAC addresses has been
  repaired.
* Some code cleanup in the UDM users/user filter for disabled and locked
  properties has been done.
* The properties allowedEmailUsers and allowedEmailGroups of groups/group
  and mail/lists have been added to the UDM module mapping.
* Searching for the IP address property of computer objects now also searches
  for IPv6 addresses.
* The gidNumber and sambaPrimaryGroupSID of users/user is now set during the
  object creation instead of setting it afterwards.