Removes HTML5Shiv from Modernizr, since it needs to be included in the head.
Replace outer-container-margin mixin with normal padding.
Removes keyframe from helpers include (since it was being duplicated in
app.css then).
Fixed footer display issue.
Minor header tweaks.
Fixes content display issue in style guide.
Updated style guide and some JS documentation.
Fixes nav display issues in IE8.
Merge pull request #191 from DoSomething/misc-stuff

Misc stuff