packaging: Allow restore to different db location

Change the engine-backup.sh utility to be able to restore a backup so
that the database will have credentials (name/host/password/etc)
different from the ones used when doing the backup.

Bug-Url: https://bugzilla.redhat.com/1002401
Change-Id: Ie2c84111808c638a1c589cf3c14c271184a0a7c2
Signed-off-by: Yedidyah Bar David <didi@redhat.com>