title: Display PDF's uploaded with paperclip
body: <p>I upload files (PDF's only) using paperclip and now want to display these as a PDF in a view.</p>
  
  <p>This gives me an empty frame <code>&lt;iframe src="&lt;% @document.file %&gt;"&gt;&lt;/iframe&gt;</code>
  This results in an image <code>&lt;%= image_tag @document.file(:large) %&gt;</code></p>
  
  <p>the files are stored in postgress.</p>