Use nav for proper HTML5 ARIA role mapping

http://www.w3.org/html/wg/drafts/html/master/sections.html#the-nav-element

http://dev.w3.org/html5/spec/sections.html#the-nav-element

http://blog.paciellogroup.com/2013/02/using-wai-aria-landmarks-2013/#tablex
Merge branch 'aria-nav' of https://github.com/kevinSuttle/bootstrap into kevinSuttle-aria-nav
fix indentation