CBLT-198: download and install couchbase-sync-gateway_0.0-109_amd64.deb

Change-Id: Ideae952b132fc3b495c787bf8ec118c92511837e
Reviewed-on: http://review.couchbase.org/34157
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>