Add styling for FileShuttle uploads.
Convert from Prism.js to Rouge.

Sorry, Prism! I love you, but Rouge has more premade plugins.
Add fallback Lexer if the language isn't found.
Add alias for Objective-C.

This is temporary. I'm going to fork Rouge and push this upstream.
Organize into modules.
Escape HTML by default.

The last commit accidentally allowed some unescaped HTML, so I've decided whitelisting HTML is a better strategy.
Return 404 if a file upload does not exist.