Upgrade to Zurb Foundation v4

#### Upgrade Zurb Foundation Framework (Fixes #99)

At last! :tada: :trumpet: :tada: :trumpet: :tada:
**Primary changes**:
* Upgrade Zurb Foundation gem to use [version 4+](http://foundation.zurb.com/docs/v/4.3.2/)
* Upgrade views to use new "large-4 columns" and "small-1 column" instead of "four columns" syntax
* Upgrade foundations_and_overrides stylesheet, including setting Zurb variabls and custom overrides.

Note: This changes about about half of all the pages on the site, so it's likely something is broken or missing - please tag any follow-up or related issues with this issue :smiling_imp:.