[fix] Convert strings to numbers if possible in .createServer

Fixes #321

Author: Southern

lib/node-http-proxy.js

@@ -74,6 +74,7 @@ exports.createServer = function () {
   //    **NEED MORE HERE!!!**
   //
   args.forEach(function (arg) {
+    arg = Number(arg) || arg;
     switch (typeof arg) {
       case 'string':   host = arg; break;
       case 'number':   port = arg; break;