The reason is that if actions are provided by rules, only one instance
exist. It was a mistake to couple actions with their notifications. It
could not work reliably and has to be removed.
The commit also change the notification action storage to be a copy
instead of the original table. This allows to append actions (not part
of this commit) without risking adding them to the wrong notification.
**WARNING** This break an unreleased API by removing the `notification`
property of an action.
Emmanuel Lepage Vallee