Replace Google Web Fonts with web-safe, cross-platform font stacks

This is good for a few reasons:
- Less reliance on Google
- Less crap to download during page load
- Uses better fonts on each platform

Font stacks from: http://css-tricks.com/snippets/css/font-stacks/

Signed-off-by: Alan Orth <alan.orth@gmail.com>
Merge pull request #12 from alanorth/font-stacks

Replace Google Web Fonts with web-safe, cross-platform font stacks