MB-100: add milticlient kv handler

Change-Id: Icc19b27ec82b5c2dd9d6de712f097f2b31aaab64
Reviewed-on: http://review.couchbase.org/25184
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>