fix Socket#close() callback support

node waits for all sockets to die instead of invoking the callback
when the listening socket is closed... seems incorrect to me but
it is what it is

lib/sockets/sock.js

@@ -147,18 +147,29 @@ Socket.prototype.closeSockets = function(){
  * Delegates to the server or clients
  * based on the socket `type`.
  *
+ * @param {Function} [fn]
  * @api public
  */
 
 Socket.prototype.close = function(fn){
   debug('closing');
   this.closing = true;
   this.closeSockets();
-  if (this.server) {
-    debug('closing server');
-    this.server.on('close', this.emit.bind(this, 'close'));
-    this.server.close(fn);
-  }
+  if (this.server) this.closeServer(fn);
+};
+
+/**
+ * Close the server.
+ *
+ * @param {Function} [fn]
+ * @api public
+ */
+
+Socket.prototype.closeServer = function(fn){
+  debug('closing server');
+  this.server.on('close', this.emit.bind(this, 'close'));
+  this.server.close();
+  fn && fn();
 };
 
 /**