* Add configure variable to disable email from reserve/notify so that
  FEs and MEs do not generate any email at all (except auto cancel).

* When creating reservations via the Portal, do not send any email any
  target cluster.

* All email is generated from the Portal now, one message for the entire
  resgroup (approved, deleted, canceled).

* Move the Announcement support from reservation to resgroup, so again
  one per group instead of an Announcement per node type and reservable
  node.