Univention Corporate Server 4.1 erratum 16 (bugfix)

This update addresses the following issues:
* The locale is not replaced by the Country syntax class anymore. This caused
  side effects in all processes which imported the UDM python modules. For
  example the translation of the appcenter UMC modules was not possible
  (Bug 39146).
* From now on domain names for mail domains will be lowercased when created
  or modified. Existing domain names will not be changed automatically, only
  when they are modified. Mixed case domain names caused inconsistent
  behaviour with Dovecot and shared folders (Bug 39721).