Update code for default server.js so no warning are displayed

When running with a newest express module, this
message is shown :

  Warning: express.createServer() is deprecated, express
  applications no longer inherit from http.Server,
  please use:

    var express = require("express");
    var app = express();
Merge pull request #1521 from mscherer/fix/nodejs/remove_warning_on_express

Merged by openshift-bot
Mongodb V2