* DistUpgrade/DistUpgrade.cfg.dapper,
  DistUpgrade/prerequists-sources.list.dapper:
  - add support for dapper->hardy upgrades
* DistUpgrade/DistUpgradeConfigParser.py:
  - add overwrite support for the configuration to support
    upgrades to multiple target releases with the same
    upgrader
* data/update-manager.schemas.in:
  - /apps/update-manager/check_dist_upgrades is deprecated
* utils/demotions.py:
  - make it more flexible to support generating both 
    dapper and gutsy demotions