Make express res.json support promise

promise.js

// Let express support "Promise"
app.use(function(req, res, next) {
  var oldResJson = res.json;
  res.json = function(promise) {
    if (promise &&
        typeof promise === 'object' &&
        typeof promise.success === 'function') {
      promise.success(function(fetchedObj) {
        if (fetchedObj) {
          oldResJson.call(res, fetchedObj);
        } else {
          next(404);
        }
      });
    } else {
      oldResJson.apply(res, arguments);
    }
  };
  next();
});