Force ribbon/carousel images to be height 200

This alters the Link.render method to let it take either a height or a width (or both or none) and only specify that in the img tag and let the browser resize. Then uses this in the ribbon in the Org page.

There is a well known problem with bootstrap overriding the specified heights in an img tag 
https://www.google.com/search?q=override+twitter+height+auto+bootstrap ... so I resorted to some ugly inline styles to force this. @ischneider can you take a look at this and suggest improvements perhaps. Wasted way too long on this and now that it works Im walking away for now.

Closes #597