Changes to add multinames to markerclusterer infowindow and change style for cluster markers.

In InfoWindow for markerclusterers we lose ability to show images
because marker infowindow and rails instance variables are gone at the
time of calling click command.

Now, I'm just pulling the friend name from marker.title which is all we
have.  We should also limit the number of names that appear on a
cluster, otherwise the window gets super long.