Univention Corporate Server 4.1 erratum 127 (bugfix)

This update addresses the following issue(s):
* Apps may define ports they want to occupy exclusively. Docker Apps checked
  before installation whether an already installed App excepts exclusive
  access to one of these ports. This check has been extended to Non-Docker
  Apps.
* Apps now show general information about the terms under which the software
  may be used. If the App ships a license file, it may be read before and
  after installation.
* Internal adaptations have been added to allow for extending App Center
  functionalities.