v0.16.1

Fixed

• A signed-in reader who asks for a missing address gets the 404 page again,
  not a plain "Not found". The Worker asked the asset store for /404.html,
  which auto-trailing-slash answers with a redirect the Worker does not
  follow; it now asks for /404, and fetches any .html file by the address
  the store serves it at. The denial suite's asset store now redirects as the
  real one does, and checks that a missing page is the 404 page.