CBQE-0: failover test:rebalance before buckets creation

Change-Id: I2870417e27b782fb8310027fb0ce165c9980eeb8
Reviewed-on: http://review.couchbase.org/34641
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>