Removes heading image on subpages. Was not serving a purpose other than clutter.
Separates nav into two sections in preparation for more robust filter data UI
Makes nav full-width. Splits nav properly into two floated halves. Adds link to documentation. Changes filter and download link to just 'data'
Adds populated documentation page
Adds styles for documentation page and adjusts site paragraph and h1 to slightly lighter weights to match new mockups.
Merge pull request #280 from 18F/feature/improve-nav

Feature/improve nav