CBQE-1703: add UI conections stats check test

Change-Id: Ib539d8c8055b50aaedc6cbd6b1f2cd448979ff87
Reviewed-on: http://review.couchbase.org/33928
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>