title: remove _id from mongo result
body: <p>I'm pretty new with mongo and nodejs 
  I've a json as result of my query and I simply want to return the result as an http request, as following:</p>
  
  <pre><code>app.get('/itesms', function(req, res) {
    items.find().toArray(function (err, array) {
      res.send(array);
    })
  });
  </code></pre>
  
  <p>It works, only problem is that I want to hide the _id fields (recursively) from the result. 
  Any suggestion to do that in an elegant way?</p>