Add dumb mode to cbc tool

This mode allows to use cbc with any memcached nodes

Change-Id: Ibb425e661caf4a75dac0dea720c9df3160833095
Reviewed-on: http://review.couchbase.org/27976
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>