title: Any type of file is been update on my rules of allowed_types
body: <p>I use CodeIgniter and I want to upload an image.
  Therefore I tried to limit the allowed file extensions using 'allowed_types'.</p>
  
  <p>However I still accepts any file extension when I upload something. </p>
  
  <p>This is a simple form. </p>
  
  <pre class="lang-php prettyprint-override"><code>$configImagem['upload_path']   = './files/noticias/imagens';
  $configImagem['allowed_types'] = 'gif|jpg|jpeg|png';
  $configImagem['file_name']     = 'noticia_'.date('y-m-d_h-i-s');
  
  $this-&gt;upload-&gt;initialize($configImagem);
  </code></pre>
  
  <p>I expect an error when I upload a file with a extension not in allowed_types.</p>