function nocache(req, res) {
  setHeader(res, 'Cache-Control', 'no-store, no-cache, must-revalidate, max-age=0');
  setHeader(res, 'Pragma', 'no-cache');
}
Forcefully add no-cache headers to HTTP responses.

@param {Request} req The incoming HTTP request.
@param {Response} res The outgoing HTTP response.
@api public