Refactor FEED_URL to constant
Fixed code scrolling CSS issue.

Also modified to use monokai instead of github CSS.

Fix referenced at http://stackoverflow.com/questions/8513099/css-overflow-culls-background-color.
Latest highlightjs
Upgrade jquery, google analytics script
Add client-side support for lang identifier.

The general idea is the same as what is found in GitHub Flavored
Markdown, except that this code uses highlight.js and a small amount of
javascript.

Above the code block to be highlighted, just add a ```lang identifier,
like ```cs for it to be marked as C#.

The implementation ultimately calls hljs.highlight(lang, code_block).
Update disqus script
Fix rack env issue
Add back feed url detection with rack fix