Fix responsive

This fixes the responsive dropdown menus so the menus work on small screens (including mobile).  Paired on this with Emily, my housemate.  It's a one-line fix and there's no tests since I don't really know how to test this at all.  The problem was that the javascript was being included twice: once in app/views/layout/application and once in app/views/layout/_meta.  I removed the one in _meta and it all works now.