Add a simple navbar that will link to the root path, about and contact actions.
Change notices and alerts to foundation alert-boxes.

 * Require Foundation in application.js because the install generator
   seems to have conveniently forgot it.
Surround the yielded template with a div.row to give some left and right margins to page content.
Add an arbitrary footer.

  * size the main page content to 50em so the footer isn't pushed to the
    top of the page.
Move links to about, contact from top bar to footer and put sign-in/out
links in their place.

  * put alerts and notices inside the page-content row, as their own
    nested rows so they don't stretch across the entire page.
  * also add a link to my github page in the footer.
Merge branch 'layout'