Univention Corporate Server 4.3 erratum 38 (bugfix)

This update addresses the following issues:
* The password dialog that is shown upfront some functions in UMC when using
  a Single Sign On (SAML) session can now be submitted by pressing Enter.
* Enhance logging for disabled memberof overlay.
* The description of the UCR variable umc/web/piwik has
  been adjusted to better reflect the actual behavior.