Shinya Sasaki

This pr closes #23

Fluentd v0.14.12 or later supports multi process workers. https://www.fluentd.org/blog/fluentd-v0.14.12-has-been-released but, this plugin was errored like this. ``` 2019-06-19 11:26:43 +0900 [error]: config error file="/etc/td-agent/td-agent.conf" error_class=Fluent::ConfigError error="Plugin 'rewrite' does not support...