add aggregation integration test
add aggregation integration test

Kubernetes-commit: 5cfe26dece13c77bd17fd10e47d2c00bf5da9b6d

caesarxuchao/sample-apiserver,kubernetes/sample-apiserver,kubernetes/sample-apiserver,kubernetes-nightly/sample-apiserver,caesarxuchao/sample-apiserver,caesarxuchao/sample-apiserver,kubernetes-nightly/sample-apiserver