Univention Corporate Server 4.2 erratum 227 (bugfix)

This update addresses the following issue(s):
* When joining into an Active Directory domain where an UCS system is already
  part of an dialog to replace this system is shown if that system is not
  reachable.
* The detection of the domaincontroller master FQDN during the initial system
  configuration has been fixed if the nameserver is not the DC Master.
* UCS App appliances now check for a valid license before starting the join
  process.
* A warning is now shown when a UCS system tries to join into a domain with
  a lower UCS version on the UCS master.