Univention Corporate Server 4.1 erratum 120 (bugfix)

This update addresses the following issue(s):
* The joinscript uses curl instead of wget to configure SAML service provider
  setting to prevent conflicts with old SHA1 or MD5 SSL certificates.
* A unjoinscript has been added which removes the SAML configuration for UMC.
* If error messages contained a "%" they weren't displayed in UMC.