message: invert QR code to support Android
diff: @@ -30,8 +30,6 @@ impl LazyMessageWriter {
  let qr_code = QrCode::new(&url)
  .expect("failed to create a QR code with the server url")
  .render::<QrUnicode::Dense1x2>()
  - .dark_color(QrUnicode::Dense1x2::Light)
  - .light_color(QrUnicode::Dense1x2::Dark)
  .quiet_zone(false)
  .build();
  