open graph and twitter link expansions
https://dev.twitter.com/cards/getting-started
see implementation on bookshare for comparison -- https://git.gmu.edu/srct/bookshare/blob/1.0/bookshare/trades/templates/detail_listing_no_auth.html
https://dev.twitter.com/cards/getting-started
see implementation on bookshare for comparison -- https://git.gmu.edu/srct/bookshare/blob/1.0/bookshare/trades/templates/detail_listing_no_auth.html