Abstract media queries and load separate stylesheet in IE8 and below

- IE8 gets:
    - Navigation
    - Article layout
    - Zone headings on fronts (used to be buggy with white text on white background)
    - No SVG data outputted in CSS (for a leaner CSS file)
    - HTML5 Elements support

@gidsg: can we look at how we can perform a global visual regression testing?

![TP](http://i.imgur.com/WGqDnNq.gif)