Added html5.js into js/lib/

Files is from here: http://html5shim.googlecode.com/svn/trunk/html5.js

That way, we don’t need to rely on external code.
Cleaned up formatting
Moved css_browser_selector into /js/lib/
Small formatting adjustment for consistency
Set index.html to use the internal htm5.js
Updated and formatted the licenses
Removed placeholder download link