Backup etherpad.o.o with bup.

* modules/openstack_project/manifests/etherpad.pp: Add the needed
bup resources to perform offsite backups of the etherpad.o.o host.
Do this now that etherpad.o.o has been migrated.

Change-Id: Icf25549529ef8cfa8a535ab58bbbc7156297ac9f
Merge "Backup etherpad.o.o with bup."