CBQE-1531: add rebalance and failover tests to query tool

Change-Id: I05b720e11077b17df17c2a83e6568adc2a7af7ad
Reviewed-on: http://review.couchbase.org/29345
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>
Tested-by: Iryna Mironava <irynamironava@yandex.ru>