Univention Corporate Server 4.2 erratum 38 (bugfix)

This update addresses the following issues:
* Progress bars are now escaping HTML content more strict.
* Start containers with the hosts proxy settings by default.
* A script can now be run after configuring an App.
* Under certain circumstances, it was possible that the CLI selected the
  wrong App version.
* AdditionalPackages defined by the App are no longer removed when
  uninstalling an app.