title: Document management with Ruby on Rails
body: <p>Anybody can recommend a good library to use for:</p>
  
  <ol>
  <li>Upload document (Office, PDFs and others) </li>
  <li>Download document </li>
  <li>Render Thumbnail and preview doc in the browser</li>
  </ol>
  
  <p>It would be best to have all of the above but 1 and 2 is good too</p>