title: PUT with 'superagent' module
body: <p>Reading <a href="https://visionmedia.github.io/superagent/#post-/-put-requests" rel="nofollow"><code>Superagent</code></a> documentation, There is no distinguish between POST &amp; PUT request : </p>
  
  <pre><code>  request.post('/user')
      .set('Content-Type', 'application/json')
      .send('{"name":"tj","pet":"tobi"}')
      .end(callback)
  </code></pre>
  
  <p>How to do PUT request using this package ?</p>