add close() api

Author: jhchen

lib/Server.js

@@ -271,6 +271,11 @@ Server.prototype.listen = function() {
 	}.bind(this));
 }
 
+Server.prototype.close = function() {
+	this.io.close();  // Will also close listeningApp
+	this.middleware.close();
+}
+
 Server.prototype.serveMagicHtml = function(req, res, next) {
 	var _path = req.path;
 	try {