title: Django RawIdWidget with checkboxes
body: <p>I have a raw_field_id with organizations:</p>
  
  <blockquote>
    <p>raw_id_fields = ('organizations',)</p>
  </blockquote>
  
  <p>This displays an input field with ID's of the selected Organizations.</p>
  
  <p>When you click on the magnifier a popup windows opens with all the Organizations listed nicely. You can click one Organization and the ID will be placed into the input field.</p>
  
  <p>Is it possible to use checkboxes to select more than one Organization?</p>