Let noDelay (disable Nagle) be set in connect options

It's not clear that it's a performance boost, so I've left it to
default to `false`, that is not disabled.

lib/connect.js

@@ -89,7 +89,7 @@ function connect(url, socketOptions) {
 
   var parts = URL.parse(url, true); // yes, parse the query string
   var protocol = parts.protocol;
-  var net;
+  var noDelay = !!sockopts.noDelay;
 
   var options = openOptionsFromURL(parts);
   var port = parts.port || ((protocol === 'amqp:') ? 5672 : 5671);
@@ -103,6 +103,7 @@ function connect(url, socketOptions) {
 
   function onConnect() {
     sockok = true;
+    sock.setNoDelay(noDelay);
     var c = new Connection(sock);
     c.open(options).then(function (_openok) { result.resolve(c); },
                          function(err) { result.reject(err); });