Univention Corporate Server 4.4 erratum 155 (bugfix)

This update addresses the following issues:
* A trivial ucr syntax error has been fixed in the joinscript
* Remove lockingdb and s4cache during re-join
* When the S4-Connector starts, it logged the group cache initialization
  at level INFO. In debugging situations that can lead to a lot of output
  in connector-s4.log which ist hard to scroll. The log volume of the
  group cache init has been lowered to log level ALL.
* The scripts remove_ucs_rejected.py and remove_s4_rejected.py now
  escapes SQL syntax.
* Avoid rejects when DNS records have an uppercase DC attribute.
* Fix traceback password sync_to_ucs for machine accounts.