Small optimization for "aq flush --hosts"
Small optimization for "aq flush --hosts"

We already have all interfaces loaded, so we can populate
Interface.master without having to query the database again.

Change-Id: Ied79f6f3ec1002ed3241df860e780c6e1f78a840
Reviewed-by: Dave Reeve <6a84ee3ae0690d4584b99406fb3076392171f50e@morganstanley.com>

quattor/aquilon,guillaume-philippon/aquilon,guillaume-philippon/aquilon,quattor/aquilon,guillaume-philippon/aquilon,quattor/aquilon