title: Getting geodjango query to return distance as an attribute?
body: <p>Is there a way to get a query to return the distance from the point for each location? 
  Right now I have <code>Location.objects.filter(geometry__distance_lte=(pnt, D(mi=20)))</code>
  but the rows don't have a distance attribute. How can I get the distance from pnt for each row that is returned?</p>