Use rouge instead of Pygments for easier page development on Windows

I've been struggling to get Jekyll working on Windows because it needs Pygments (for syntax highlighting) which is in fact a Python module and the Ruby-Python mix seems quite difficult on Windows. I followed dozen of recipes without any success. I found that rouge, a pure-Ruby replacement, could be used instead of Python. This fixes all my problems and the site displays perfectly (same result as with Pygments on GitHub). I plan to write a short documentation about that to avoid others the same nightmare... And I agree with James that we need web site contributors to run Jekyll before sending pull requests as Jekyll as some differences with markdown accepted in other places on GitHub.

I could have my own version of _config.yml but with the risk of commiting it at some point... I'd suggest switching to rouge on the web site. I could not find an explicit mention that this is supported by GitHub but as Jekyll is developped by GitHub, I cannot imagine this is not the case.

I don't see other ways of testing that merging this pull request and revert it in case of problems...

Feedback/comments welcome!

Michel