CBQE-2297: upr rebalance scenarios for testrunner

initial checkin of test cases that perform rebalance/failovers
while verifying mutations using upr client

Change-Id: Ic8b5f2a21929c9f27e43b3001eff839855367ad4
Reviewed-on: http://review.couchbase.org/38773
Reviewed-by: Tommie McAfee <tommie@couchbase.com>
Tested-by: Tommie McAfee <tommie@couchbase.com>