Fix Non-idempotent tasks:

The following tasks are not idempotent and fail on a secondary run:
TASK [kubernetes : Start master node] ******************************************
task path: /home/xenith/git/easy-kube/roles/kubernetes/tasks/main.yml:28
skipping: [easy-kube-node] => {"changed": false, "skip_reason": "Conditional check failed", "skipped": true}
fatal: [easy-kube-master]: FAILED! => {"changed": true, "cmd": "kubeadm init", "delta": "0:00:02.758070", "end": "2016-10-02 19:16:12.439757", "failed": true, "rc": 1, "start": "2016-10-02 19:16:09.681687", "stderr": "error: <util/kubeconfig> failed to create \"/etc/kubernetes/kubelet.conf\", it already exists [open /etc/kubernetes/kubelet.conf: file exists]", "stdout": "<master/tokens> generated token: \"694090.2692006d9db049d3\"\n<master/pki> created keys and certificates in \"/etc/kubernetes/pki\"", "stdout_lines": ["<master/tokens> generated token: \"694090.2692006d9db049d3\"", "<master/pki> created keys and certificates in \"/etc/kubernetes/pki\""], "warnings": []}

TASK [kubernetes : Get the token id from the master initialisation] ************
task path: /home/xenith/git/easy-kube/roles/kubernetes/tasks/main.yml:34
skipping: [easy-kube-node] => {"changed": false, "skip_reason": "Conditional check failed", "skipped": true}

TASK [kubernetes : Register nodes with master] *********************************
task path: /home/xenith/git/easy-kube/roles/kubernetes/tasks/main.yml:40
fatal: [easy-kube-node]: FAILED! => {"failed": true, "msg": "the field 'args' has an invalid value, which appears to include a variable that is undefined. The error was: 'dict object' has no attribute 'kubeadm_token'\n\nThe error appears to have been in '/home/xenith/git/easy-kube/roles/kubernetes/tasks/main.yml': line 40, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n- name: Register nodes with master\n  ^ here\n"}

NO MORE HOSTS LEFT *************************************************************
        to retry, use: --limit @/home/xenith/git/easy-kube/create-cluster-playbook.retry

PLAY RECAP *********************************************************************
easy-kube-master           : ok=8    changed=0    unreachable=0    failed=1
easy-kube-node             : ok=8    changed=0    unreachable=0    failed=1
danpilch / easy-kubeadm

Fix Non-idempotent tasks: #5
