Fix etcd cert generation to support large deployments
Fix etcd cert generation to support large deployments

Due to bash max args limits, we should pass all node filenames and
base64-encoded tar data through stdin/stdout instead.

Fixes #832

Atoms/kubespray,ayaz/kubespray,kubernetes-incubator/kubespray,kubernetes-sigs/kubespray,kubespray/kargo,kubernetes-incubator/kargo,Abdelsalam-Abbas/kubespray_fork,galthaus/setup-kubernetes,kubernetes-incubator/kargo,kubernetes-sigs/kubespray,rogerwelin/kargo,ayaz/kubespray,insequent/kargo,Lendico/kargo,galthaus/setup-kubernetes,Abdelsalam-Abbas/kubespray_fork,sgm-media/kargo,Atoms/kubespray,Lendico/kargo,VincentS/kargo,Atoms/kubespray,rogerwelin/kargo,sgm-media/kargo,VincentS/kargo,hatch-k8s/kargo,kubernetes-sigs/kubespray,insequent/kargo,kubernetes-incubator/kubespray,kubespray/kargo,hatch-k8s/kargo,Atoms/kubespray,kubernetes-sigs/kubespray