Feature/actstream reversion
Put revision and version references into activities so we can build a unified activity stream with fields changed.
Requires actions are done in a new 'action block'
with DoAction() as action, reversion.create_revision():
self.state = STATE_CANCELLED
self.save()
action.set(actor=actor, verb='cancelled trip', target=self, state=STATE_CANCELLED, style='trip-cancelled')
Our action.set
very similar to actstream's action.send
.