Remove double link, media and video card types

Not sure how controversial this is but here we go...

Because we have far too many card components (20) this is a little clean up of the unused ones.

https://github.com/search?q=double_link_card+user%3Alonelyplanet&type=Code
https://github.com/search?q=meda_card+user%3Alonelyplanet&type=Code
https://github.com/search?q=video_card+user%3Alonelyplanet&type=Code