MB-6972:  first try supporting Debian 7 packages

Change-Id: Ib8ca70b5ae257ad398ad3d7d28b3bbe603e06e32
Reviewed-on: http://review.couchbase.org/41537
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>