CBQE-2119: added tests for pause and resume for rebalance scenarios

Change-Id: If3704af4f7e72cc32d9febd705475e09fc534010
Reviewed-on: http://review.couchbase.org/34475
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>