Description of problem:
/etc/origin/master/ca.serial.txt is only on the origin first master. When the first master is broken or the sequence of masters is changed in inventory file, the node_certificates may fail for there isn't /etc/origin/master/ca.serial.txt on the other masters.

Version-Release number of the following components:
openshift-ansible-3.6.140

How reproducible:
always 

Steps to Reproduce:
1. install HA OCP 3.6
2. adjust the sequence of masters in inventory file.
3. redeploy node certification or scaleup node
   ansible-playbook /usr/share/ansible/openshift-ansible/playbooks/byo/openshift-cluster/redeploy-node-certificates.yml
   ansible-playbook /usr/share/ansible/openshift-ansible/playbooks/byo/openshift-node/scaleup.yml


Actual results:
TASK [openshift_node_certificates : Generate the node client config] ***********
failed: [openshift-210.lab.eng.nay.redhat.com -> openshift-182.lab.eng.nay.redhat.com] (item=openshift-210.lab.eng.nay.redhat.com) => {
    "changed": true, 
    "cmd": [
        "/usr/local/bin/oc", 
        "adm", 
        "create-api-client-config", 
        "--certificate-authority=/etc/origin/master/ca.crt", 
        "--client-dir=/etc/origin/generated-configs/node-openshift-210.lab.eng.nay.redhat.com", 
        "--groups=system:nodes", 
        "--master=https://openshift-220.lab.eng.nay.redhat.com:8443", 
        "--signer-cert=/etc/origin/master/ca.crt", 
        "--signer-key=/etc/origin/master/ca.key", 
        "--signer-serial=/etc/origin/master/ca.serial.txt", 
        "--user=system:node:openshift-210.lab.eng.nay.redhat.com", 
        "--expire-days=730"
    ], 
    "delta": "0:00:00.244486", 
    "end": "2017-07-10 22:59:01.502011", 
    "failed": true, 
    "item": "openshift-210.lab.eng.nay.redhat.com", 
    "rc": 1, 
    "start": "2017-07-10 22:59:01.257525", 
    "warnings": []
}

STDERR:

error: --signer-serial, "/etc/origin/master/ca.serial.txt" must be a valid file
See 'oc adm create-api-client-config -h' for help and examples.

Expected results:


Expected results:

Additional info:
/usr/share/ansible/openshift-ansible/playbooks/byo/openshift-cluster/redeploy-certificates.yml works well.