title: Carrierwave - Upload from remote image url with no file extension
body: <p>When trying to upload an image using remote_image_url with Rails and Carrierwave, an error response is returned if the url doesn't have a file extension.</p>
  
  <p>"Failed to manipulate with rmagick, maybe it is not an image? Original Error: no encode delegate for this image format"</p>
  
  <p>For example, "http://1.gravatar.com/blavatar/999116b97a3284a6b130eda28e875f47?s=300" fails.
  Where as "http://1.gravatar.com/blavatar/999116b97a3284a6b130eda28e875f47.png" works.</p>
  
  <p>Is there an easy way to fix this?</p>