add specs with 2 and 3 sgw instances

as temporary solution

Change-Id: I180017d57ac26929922dd749190b4a5496e3d27e
Reviewed-on: http://review.couchbase.org/36976
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>