11520 responsive slideshow

This adds new SASS files for all the primary stylesheets. They are still 95% css, but this will change slowy over time as we rewrite portions of the files for various reasons. We can also now add global variables, mixins, etc, which should help to neaten up our stylesheets.

This also HIDES the slideshow on mobile, but fixes the layout for the deskop & tablet verions.

Mobile support will be added to the slideshow a little later on.