Revamped openchange_cleanup.py

This is now usable again.

• Don't delete password files in mapistoreCleanup()
• reworked the ldb cleanup and enabled it
• sql cleanup should now be able to figure out the db info from the config
  regardless of the format used (xml, plist, sogo.conf or GNUstepDefaults)
  (We really need a python plist parser.. the current solution is not elegant)
• Inform user of missing python packages