Update static site generator from StaticMatic to Middleman

Looking at the sign off [here](https://groups.google.com/forum/?hl=en&fromgroups#!topic/staticmatic/tkGj2eFt7yM) the creator of StaticMatic recommends Middleman which appears to be alive and strong, with active maintainers, and many support libraries.

I stumbled upon staticmatic while studying the haml.info site and wanted to update the static site generator.

I was thinking about making changes in addition to this including trying to get a few localisations in the site, as well as add some jQuery, and maybe try to make some improvements to the site.

(this is my first pull request so sorry if I did something wrong)