Univention Corporate Server 3.2 erratum 42 (bugfix)

This update fixes several issues:
* The protocol of a printer URI in the printers UMC module was always set to
  "cups-pdf://".
* Improved branding support in UMC widgets
* Reversed the traceback when sending errors via mail since the web or mail
  client could truncate important information.
* Fixed MultiSelect widget setting its values too early which could break page
  rendering.