Add support for RKE kubernetes implementation

Added a new playbook rke.yml and role rke which uses rancher RKE:
https://github.com/rancher/rke

It's an implementation of the kubernetes from rancher.com folks
and it is an alternative to the official kubernetes tool: kubeadm.

NOTE: Rancher has a notion of a 'control plane' which cannot run with
etcd on all nodes in a multi-node setup. Control-plane node is the
first kubernetes node from the inventory (as of now).

Change-Id: I0bf669442a5183efa20d44fb1cac823e7ce54348
Issue-ID: OOM-1778
Signed-off-by: Petr Ospalý <p.ospaly@partner.samsung.com>
Signed-off-by: Michal Zegan <m.zegan@samsung.com>
diff --git a/ansible/roles/rke/tasks/rke_node.yml b/ansible/roles/rke/tasks/rke_node.yml
new file mode 100644
index 0000000..9ec9f07
--- /dev/null
+++ b/ansible/roles/rke/tasks/rke_node.yml
@@ -0,0 +1,11 @@
+---
+- name: Create a rke user on the node
+  user:
+    name: "{{ rke_username }}"
+    groups: docker
+    password_lock: yes
+
+- name: Distribute rke user ssh public key
+  authorized_key:
+    user: "{{ rke_username }}"
+    key: "{{ hostvars[groups['infrastructure'][0]].cluster_public_key }}"