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* addition of flagging
* new fields on ModeratedObject
* small changes to the admin
* new GATEKEEPER_STATUS_ON_FLAG setting
* addition of custom manager and properties added to registered models
* removal of gatekeeper.approved/rejected/pending (replaced by new filters on QuerySets)
* ModeratedObject field names changed
* status - moderation_status
* moderation_by - moderated_status_by
* moderation_date - moderation_status_date
* BUGFIX: use DEFAULT_FROM_EMAIL for sending mail (was hardcoded address)
* BUGFIX: ModeratedObjectManager.get_for_instance