This pull request wraps the breadcrumb component in a `<nav>` element per recommendations from:
* http://stackoverflow.com/questions/25326699/proper-aria-handling-of-breadcrumb-navigation
* http://www.uvd.co.uk/blog/accessible-breadcrumbs-using-aria/
* https://gist.github.com/jonathantneal/4037764

And it employs the role="breadcrumbs" as shown in the W3C list found here: http://www.w3.org/TR/2007/WD-aria-role-20070601/#breadcrumbs

Remove the aria roles