rejig ClusterFormMetaclass to account for the possibility of abstract subclasses that don't specify a model yet
revert to real SQL querysets once a relation is committed to the db
specify an 'objects' manager on EventItem; otherwise future_objects becomes the default manager. Oops.
Fix TransientModelFormSet to handle db-backed entries correctly
massive robustness fixes to django-cluster
port eventhandlers over to ClusterForm
EditHandlers no longer need to accept data/files as args
EditHandlers no longer need to implement is_valid, pre_save or post_save