adding titles and summaries to social media share links

I added parameters into the links instead of using Open Graph tags (og tags) as discussed with Dak. OG tags give us more control over what displays when shared, especially in Twitter. But, this is still a big improvement over what we have now.
I don't think it's necessary to have this on both `media.coffee` and `title.coffee`, since both views will always be loaded together.  `title.coffee` does not appear to refresh when the abstract changes anyway, so it's probably superfluous.