title: Paperclip Resize to fit a rectangular box
body: <p>I have a rectangular image for example 30x800 pixels</p>
  
  <p>How I can scale it with paperclip to preserve the aspect ratio to a 100x100 pixel image with borders filling the empty area ? </p>
  
  <p>an example : <a href="http://www.imagemagick.org/Usage/thumbnails/pad_extent.gif" rel="noreferrer">http://www.imagemagick.org/Usage/thumbnails/pad_extent.gif</a></p>