using solr index instead of querying each object

This pull request decreases the load time by 90% when browsing the catalog page.  On production servers clicking the next button can take between 6 and 10 seconds.  That's a long time and about 250+ http requests to Fedora and Solr.  The end result is a frustrated user and a server that is overwhelmed.

I found one issue with this new code.  If the thumbnail doesn't exist on a moving image the request for the image returns 500 and shows the user a broken image.  I'm thinking /master_files/avalon:8/thumbnail could return no_icon.png if it can't find the thumbnail.  Or just store some information about the thumbnail in solr on the media object.