HTML5 styling in IE8 and below

I added html5shiv to the template, so that HTML5 elements such as <article> can be styled in IE8 and below.

More info about what and why can be found [here](http://diveintohtml5.info/semantics.html#unknown-elements).

Thanks to enridp and wlangstroth: https://github.com/cloudhead/less.js/issues/571

This is a fix for https://github.com/cloudhead/lesscss.org/issues/9