Univention Corporate Server 4.2 erratum 196 (bugfix)

This update addresses the following issue(s):
* The max open files soft limit of the UMC-Server has been raised.
* The SAML authentication robustness has been improved. Errors during LDAP
  authentication now contain more information about the cause.
* An UMC-Server crash which happened occasionally is prevented.
* The text of app and module tiles is now resized dynamically e.g. when the
  screen size changes.