MB-24313: Add server to client communication
MB-24313: Add server to client communication

Start discussing the "overall on the wire framing" used
to make the communication pipe full duplex.

Change-Id: Ia9b3235218eb497af1ce84b4c4352f415b5ce272
Reviewed-on: http://review.couchbase.org/78068
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

couchbase/memcached,daverigby/kv_engine,couchbase/memcached,couchbase/memcached,couchbase/memcached,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine