Univention Corporate Server 4.2 erratum 41 (bugfix)

This update addresses the following issue:
* The unmaintained and deprecated internal test suite has been removed.
* Fix handling of "Change password on next login" for new user accounts.
* Support for forwarding user emails to external addresses has been added.
* The error handling regarding LDAP size limits has been improved.
* Creating computers with IPv6 addresses is possible again.
* Fix typo in users/user when reading the minimal password length.
* The default value of extended attributes which don't define any default
  has been changed from "" to None.
* A regression in UCS 4.2 has been fixed which caused that DHCP pools
  which have values unknown by UDM in its dhcpPermitList could not be
  opened or modified anymore.
* The font color on the portal page can be configured now.