Fluent send via UDP

Hi folks

I've tried to send logs to fluentd with this code
`from fluent import sender
logger = sender.FluentSender('app', host='127.0.0.1', port=24224)
logger.emit('test', {'from': 'localhost', 'to': 'fluentd'})
logger.close()
`

And success!
Now, do you have idea to send that via udp?
If it's already the feature, please write it on readme.md. I think I'm not only one who wants to send logs via UDP.

Thank you!