title: custom paperclip validation error message
body: <p>I have this validation for content type:    </p>
  
  <pre><code>validates_attachment_content_type :photo, :content_type =&gt; /^image\/(jpg|jpeg|pjpeg|png|x-png|gif)$/, :message =&gt; 'file type is not allowed (only jpeg/png/gif images)'
  </code></pre>
  
  <p>I want only the message above to be displayed but instead it says </p>
  
  <pre><code> Photos photo content type file type is not allowed (only jpeg/png/gif images)
  </code></pre>
  
  <p>because its a photos model and attached file photo.</p>
  
  <p>thanks</p>