title: HTMLPurifier config error
body: <p>I'm trying to set some configurations for HTMLPurifier, and everything works on my dev machine, but on test, it fails. </p>
  
  <p>with the error Class 'HTMLPurifier_config' not found.
  but if I remove config, it runs no problem. 
  I'm using HTMLPurifier 4.0.0</p>
  
  <pre><code>$config=HTMLPurifier_config::createDefault();
  $config-&gt;set('AutoFormat','AutoParagraph', true);
  $config-&gt;set('AutoFormat','Linkify', true);
  
  $purifier = new HTMLPurifier($config);
  </code></pre>
  
  <p>I am loading HTMLPurifier with HTMLPurifier.auto.php, but as I said, this is working in dev, but not testing.</p>