add highlight.js and tomorrow-night-eighties.css to comm-plat assets
conditionally add highlightjs assets for duckduckhack pages
add page_class to docs for targeted CSS
whoops, fix tomorrow-night-eighties href
Switch tomorrow-night-eighties to tomorrow-night
Merge pull request #330 from duckduckgo/zaahir/add-highlightjs

Add syntax highlighting to DuckDuckHack docs