Univention Corporate Server 4.0 erratum 106 (bugfix)

The following issues are addressed by this update:
* A default time-out of 10 minutes was added to the updater, after which
  stalled HTTP connections are aborted.
* A confirmation dialogue is now prompted when the browser window is closed
  or the page is reloaded during an update process.
* univention-add-app now prevents the installation of apps on the wrong
  server role