Univention Corporate Server 4.1 erratum 58 (bugfix)

This update addresses the following issues:
* UCS-3.0 errata updates are no longer mirrored with newer systems.
* Fix inheritance of using https:// scheme for components.
* If no update process is currently running the UMC module won't block
  closing UMC anymore.
* The update process via the UMC module can be started if the logfiles don't
  exist.
* The HTTP timeout has been reduced to 30 seconds.
* Some shell quoting errors were fixed.
* A vulnerability has been fixed which could lead to code execution.
* A progressbar is now shown while rebooting the system.