Update to foundation 4.0

This updates the theme to comply with Foundation 4.0. I needed to copy of a few css directives from 3.0 in order to keep the nav's style (see dba4bc8), This was the simplest way I could think of keeping the integrity of the theme, without editing bones files.

The new css isn't generated with sass, but it would be simple to do that if someone else wants to take that. Just generate the new sass file into stylesheets/foundation.css