New mobile responsive site design

Redesigned site using Foundation ZURB 5. Site is mobile responsive and very
mono-grayscale. Beta version of the theme - more work needs to be done.
Rename #TODOs to TODOs

Rename #TODOs in blog posts to TODOs so they aren't caught in my grep/find
tools as false positives.
Update SFML blog post to use image include

A new left-float image include was written with the new theme, and the SFML
blog post was changed to take advantage of this syntax.
Add 'html-proofer' gem and rake test target

Add a gem and rake target for testing and validating the links and document
structure of the generated site.