Serialise operations on components which may be highly available

Minimal playbook changes to reduce the risk out outages. This
could be further improved by contacting the elasticsearch API
during actions to ensure that each node recovers before moving
on to the next.

Change-Id: If106efd5700c770a8256adb11cb4735d11cbed5c

elk_metrics_7x/installElastic.yml

@@ -14,7 +14,7 @@
 - name: Install Elastic Search
   hosts: elastic:kibana
   become: true
-
+  serial: 1
   vars_files:
     - vars/variables.yml
 

elk_metrics_7x/installKibana.yml

@@ -14,6 +14,7 @@
 - name: Install Kibana
   hosts: kibana
   become: true
+  serial: [1, '100%']
   vars_files:
     - vars/variables.yml
 

elk_metrics_7x/installLogstash.yml

@@ -14,6 +14,7 @@
 - name: Install Logstash
   hosts: logstash
   become: true
+  serial: [1, '100%']
   vars_files:
     - vars/variables.yml