subdoc: Update to C++ subjson API
subdoc: Update to C++ subjson API

Change-Id: Ifbdfd5256c4f4fee5ffd5da9e5611ea251ce48f2
Reviewed-on: http://review.couchbase.org/50980
Reviewed-by: Mark Nunberg <dab05a0fe859c5cb93882b2a75a0d613501b07be@couchbase.com>
Tested-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

owendCB/memcached,daverigby/memcached,couchbase/memcached,couchbase/memcached,cloudrain21/memcached-1,daverigby/kv_engine,daverigby/kv_engine,cloudrain21/memcached-1,owendCB/memcached,daverigby/memcached,couchbase/memcached,owendCB/memcached,daverigby/memcached,cloudrain21/memcached-1,daverigby/kv_engine,owendCB/memcached,daverigby/memcached,daverigby/kv_engine,couchbase/memcached,cloudrain21/memcached-1