CBQE-2441: n1ql add rebalance+ joins, subqueries tests

Change-Id: Icdc1609ea5f4ba8f4bc229aec7ec27da0272d242
Reviewed-on: http://review.couchbase.org/42469
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>