title: PUTing files into S3 using Python requests
body: <p>I've got this URL that was generated using the <code>generate_url(300, 'PUT', ...)</code> method and I'm wanting to use the <a href="http://python-requests.org/" rel="nofollow">requests library</a> to upload a file into it.</p>
  
  <p>This is the code I've been using: <code>requests.put(url, data=content, headers={'Content-Type': content_type})</code>, I've also tried some variations on this but the error I get is always the same.</p>
  
  <p>I get a 403 - <code>SignatureDoesNotMatch</code> error from S3 every time, what am I doing wrong?</p>