Automatic merge from submit-queue

Bump up addon kube-dns to v20 for graceful termination

Below images are built and pushed:
- gcr.io/google_containers/kubedns-amd64:1.8
- gcr.io/google_containers/kubedns-arm:1.8
- gcr.io/google_containers/kubedns-arm64:1.8
- gcr.io/google_containers/kubedns-ppc64le:1.8

Both kubedns and dnsmasq are bumped up in the manifest files.

@thockin @bprashanth