ux-off-canvas uses an aria role incorrectly

[ScottMaclure]

https://github.com/GoogleChrome/accessibility-developer-tools/wiki/Audit-Rules#ax_aria_10

Many ARIA attributes (states and properties) can only be used on elements with particular roles.

<a class="left-off-canvas-toggle menu-icon" aria-expanded="false"><span></span></a>

http://foundation.zurb.com/docs/components/offcanvas.html