Upgrade Kubernetes to V1.11.2
The kubeadm configuration file version has been upgraded from v1alpha1 to v1alpha2
Add bootstrap kubeadm-config.yaml with external etcd

Use helm install or support in future

Even without this PR, the operation works well.
However, it is better to use a single slash rather than
a double slash in the path.

This fixes #3014

apiserver cert should be created only once

ingress-nginx 0.16.2 (https://github.com/kubernetes/ingress-nginx/releases/tag/nginx-0.16.2)

This patch simplify ingress-nginx deployment by default deploy on
master, with customizable options; on the other hand, remove the
additional Ansible group "kube-ingress" and its k8s node label
injection.

Reference to https://kubernetes.io/docs/concepts/services-networking/ingress/#prerequisites:

    GCE/Google Kubernetes Engine deploys an ingress controller on the master.

By changing `ingress_nginx_nodeselector` plus custom k8s node
label, user could customize the DaemonSet deployment target.

If `ingress_nginx_nodeselector` is empty, will deploy DaemonSet on
every k8s node.

The referenced issue (https://github.com/kubernetes/kubeadm/issues/441) has already been fixed.

* Add tags for cert serial tasks

This will help facilitate tag-based deployment of specific components.

* fixup kubernetes node

The number of pods on a given node is determined by the  --max-pods=k
directive. When the address space is exhausted, no more pods can be
scheduled even if from the --max-pods-perspective, the node still has
capacity.

The special case that a pod is scheduled and uses the node IP in the
host network namespace is too "soft" to derive a guarantee.

Comparing kubelet_max_pods with kube_network_node_prefix when given
allows to assert that pod limits match the CIDR address space.

* Upgrade k8s to 1.10.2

Bumped etcd version to 3.2.16 as recommended

* Add ipvs fix for v1.10

* change flannel addons test to ha