CBLT-42:  the packagers all expect the staging dir to be:

    app-under-test/sync_gateway/build/opt/couchbase-sync-gateway

Change-Id: I0b8ce3619253aad837d4de6c77a30cde12736b79
Reviewed-on: http://review.couchbase.org/37244
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>