Implement hosted web font kit

- Add link to hosted CSS file to default layout `head`
- Update CSS font names

Note that this kit uses style linking, so it is now unnecessary to
specify the specific font variant in the `font-family` name.
Change hosted webfont URL to protocol-agnostic
Remove obsolete fonts.css file
Merge pull request #23 from Scotchester/gh-pages

Implement hosted webfont kit