Univention Corporate Server 4.4 erratum 203 (bugfix)

This update addresses the following issue(s):
* The security for authentication requests has been improved.
* The progress bar interval is now configurable via the backend of modules.
* It is now prevented that the UMC-Webserver creates multiple new connections
  for a session after the connection to the UMC-Server was closed and
  multiple parallel requests from the old session are requested.
* Multiple parallel authentication requests are now correctly handled by the
  UMC-Webserver.