"Show Affiliations" button -- make keyboard & screenreader accessible

[lhenze]

From NYU A11y Review:

Show Affiliations element does not follow expected pattern.

The "Show Affiliations" element (coded as a link) is not in the taborder (and not available to the keyboard-only user) and the screen reader user hears it as "clickable", but does not understand what it does when it is 'clicked". This element has characteristics of a "disclosure" (e.g. - "show/hide") model. Refer to the WAI-ARIA authoring practices for disclosure.