Automatic merge from submit-queue (batch tested with PRs 41349, 41532, 41256, 41587, 41657)
Update kubectl in addon-manager to use HPA in autoscaling/v1
Addon-manager is broken since HPA objects were removed from extensions api group.
Came across the logs from [the latest addon-manager on Jenkins](https://storage.googleapis.com/kubernetes-jenkins/logs/ci-kubernetes-e2e-gci-gce/4290/artifacts/bootstrap-e2e-master/kube-addon-manager.log):
```
INFO: == Entering periodical apply loop at 2017-02-16T17:33:37+0000 ==
error: error pruning namespaced object extensions/v1beta1, Kind=HorizontalPodAutoscaler: the server could not find the requested resource
WRN: == Failed to execute /usr/local/bin/kubectl apply --namespace=kube-system -f /etc/kubernetes/addons --prune=true -l kubernetes.io/cluster-service=true --recursive >/dev/null at 2017-02-16T17:33:38+0000. 2 tries remaining. ==
error: error pruning namespaced object extensions/v1beta1, Kind=HorizontalPodAutoscaler: the server could not find the requested resource
WRN: == Failed to execute /usr/local/bin/kubectl apply --namespace=kube-system -f /etc/kubernetes/addons --prune=true -l kubernetes.io/cluster-service=true --recursive >/dev/null at 2017-02-16T17:33:46+0000. 1 tries remaining. ==
error: error pruning namespaced object extensions/v1beta1, Kind=HorizontalPodAutoscaler: the server could not find the requested resource
WRN: == Failed to execute /usr/local/bin/kubectl apply --namespace=kube-system -f /etc/kubernetes/addons --prune=true -l kubernetes.io/cluster-service=true --recursive >/dev/null at 2017-02-16T17:33:53+0000. 0 tries remaining. ==
WRN: == Kubernetes addon update completed with errors at 2017-02-16T17:33:58+0000 ==
```
And notice this commit (f66679a4e9) came in two weeks ago, which removed HorizontalPodAutoscaler from extensions/v1beta1.
Addon-manager is now partially functioning that it could successfully create and update addons, but will fail to prune objects, which means upgrade tests may mostly fail.
Pushed another version of addon-manager with kubectl v1.6.0-alpha.2 ([release 2 days ago](https://github.com/kubernetes/kubernetes/releases/tag/v1.6.0-alpha.2)) for fixing, including below images:
- gcr.io/google-containers/kube-addon-manager:v6.4-alpha.2
- gcr.io/google-containers/kube-addon-manager-amd64:v6.4-alpha.2
- gcr.io/google-containers/kube-addon-manager-arm:v6.4-alpha.2
- gcr.io/google-containers/kube-addon-manager-arm64:v6.4-alpha.2
- gcr.io/google-containers/kube-addon-manager-ppc64le:v6.4-alpha.2
- gcr.io/google-containers/kube-addon-manager-s390x:v6.4-alpha.2
@mikedanese
cc @wojtek-t @shyamjvs
fe34705f8a