Add support to enable NDELAY with HELLO

Change-Id: I27bde67a216c85be0f0ced3280d66ecc03d990f4
Reviewed-on: http://review.couchbase.org/42340
Reviewed-by: Daniel Owen <owend@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>