syntax highlighting

[btel]

The python code examples are not syntax highlighted:

[rgaiacs]

http://kramdown.gettalong.org/syntax.html#language-of-code-blocks says that we should use .language-ruby instead of .python and we still need to add the CSS. :-(

[gvwilson]

We've had complaints in the past from some users about syntax highlighting because their code isn't highlighted the same way, which confuses them.