Nukes system message styles & softens .error red
Styles to match the mocks & documentation update
Updated nav styles for new taglines. Hides taglines on tablet.
Switch nav order in template.
Merge pull request #188 from DoSomething/nav-updates

Updated nav styles for new taglines. Hides taglines on tablet.
Adds close messages functionality
Changes letter "x" to unicode cross "×"
Abstracts "close modal" style and applies to messages and modals
Merge pull request #190 from DoSomething/system-message-styles

System Message Styles
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.
Sets the global footer background color to black
Removes search and logo styles from footer
Widens social wrapper to fill new space
Fixes content display issue in style guide.
Updated style guide and some JS documentation.
Fixes nav display issues in IE8.