Update: start server to use ipv4 by default

[molee1905]

see Update: start server to use ipv4 by default #12

Awesome ! qr code is now available from command line when start fis server. But there is still one stutation, for example, if a url is not ending with 'index.html' but 'xxx/yy/test.html', (http://192.168.1.100:8080/xxx/yy/test.html) , the qrcode in command line seems powerless. I still perfer to open ip not 127.0.0.1, or would you give some insights why not use ip by default?

Or is it possible to regenerate qr code when the url changes?