CBQE-928: offline_cluster_upgrade with settings verification

Change-Id: I8db9531dbf3d5e7415cf1168f14fb806432bcb4b
Reviewed-on: http://review.couchbase.org/23687
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>