#276941: Remove mail / no mail options from group types : Move update patch to og_notifications; Add migration.

#276941: Move admin messages to notifications_lite rather than use messaging directly. Invite support is no longer being handled by og_notifications. notifications_lite is now a new prereq.

.install: Typo fixes + add a @todo.

* Updated German translation

#264615: Restrict node types under Group subscriptions.