title: Mongoose Model.count() does not run callback as documented
body: <p>I am following almost <a href="http://mongoosejs.com/docs/api.html#model_Model.count" rel="nofollow">the exact example for Model.count()</a> from the Mongoose docs:</p>
  
  <pre><code>User.count({ type: 'jungle' }, function (err, count) {
    console.log('I do not ever run');
  });
  </code></pre>
  
  <p>This should print 'I do not ever run'. Instead, it returns a Query object - which should not happen, according to the docs, as I am providing a callback. How can I make the callback function run? Is there some circumstances where the callback is not run?</p>
  
  <p>Using mongoose@3.6.17. Thanks!</p>