This replaces kube-master with kube_control_plane because of [1]:
The Kubernetes project is moving away from wording that is
considered offensive. A new working group WG Naming was created
to track this work, and the word "master" was declared as offensive.
A proposal was formalized for replacing the word "master" with
"control plane". This means it should be removed from source code,
documentation, and user-facing configuration from Kubernetes and
its sub-projects.
NOTE: The reason why this changes it to kube_control_plane not
kube-control-plane is for valid group names on ansible.
[1]: https://github.com/kubernetes/enhancements/blob/master/keps/sig-cluster-lifecycle/kubeadm/2067-rename-master-label-taint/README.md#motivation
* Use K8s 1.15
* Use Kubernetes 1.15 and use kubeadm.k8s.io/v1beta2 for
InitConfiguration.
* bump to v1.15.0
* Remove k8s 1.13 checksums.
* Update README kubernetes version 1.15.0.
* Update metrics server 0.3.3 for k8s 1.15
* Remove less than k8s 1.14 related code
* Use kubeadm with --upload-certs instead of --experimental-upload-certs due to depricate
* Update dnsautoscaler 1.6.0
* Skip certificateKey if it's not defined
* Add kubeadm-conftolplane.v2beta2 for k8s 1.15 or later
* Support kubeadm control plane for k8s 1.15
* Update sonobuoy version 0.15.0 for k8s 1.15
