[AwsBeanstalkPluginExtension](https://github.com/classmethod/gradle-aws-plugin/blob/59bb90e525da2e06214ca85d586125741401b3c2/src/main/java/jp/classmethod/aws/gradle/elasticbeanstalk/AwsBeanstalkPluginExtension.java) should support multiple environments (e.g., staging, production, etc).
