message: Add middleware for security headers.
diff: @@ -14,6 +14,13 @@ app
  .then(() => {
  const server = express();
  + server.use((req, res, next) => {
  + // Express middleware to add security headers to the responses.
  + res.header('X-Content-Type-Options', 'nosniff');
  + res.header('X-Frame-Options', 'SameOrigin');
  + next()
  + })
  +
  // Handle favicon requests that ignore our HTML meta tags.
  server.get('/favicon.ico', (req, res) => (
  res.status(200).sendFile('favicon.ico', {root: __dirname + '/src/static/images/favicons/'})
  