title: Implement an image library with paperclip
body: <p>I have a few models(<code>Article, Category</code>) that all have pictures. The paperclip logic for the picture is extracted at a class <code>ContentPicture</code>.</p>
  
  <p>When uploading a picture to Article I would like to select from the already existing ContentPictures or to upload a new one. Does anyone know for gem that could handle the image library <strong>"view already uploaded, select or upload a new one"?</strong></p>