Add graceful upgrade process

Based on #718 introduced by rsmitty.

Includes all roles and all options to support deployment of
new hosts in case they were added to inventory.

Main difference here is that master role is evaluated first
so that master components get upgraded first.

Fixes #694

roles/upgrade/post-upgrade/tasks/main.yml

@@ -1,5 +1,5 @@
 ---
 
 - name: Uncordon node
-  command: kubectl uncordon {{ ansible_hostname }}
+  command: "{{ bin_dir }}/kubectl uncordon {{ ansible_hostname }}"
   delegate_to: "{{ groups['kube-master'][0] }}"

roles/upgrade/pre-upgrade/tasks/main.yml

@@ -1,11 +1,11 @@
 ---
 
 - name: Cordon node
-  command: kubectl cordon {{ ansible_hostname }}
+  command: "{{ bin_dir }}/kubectl cordon {{ ansible_hostname }}"
   delegate_to: "{{ groups['kube-master'][0] }}"
 
 - name: Drain node
-  command: kubectl drain --force --ignore-daemonsets --grace-period 30 --delete-local-data {{ ansible_hostname }}
+  command: "{{ bin_dir }}/kubectl drain --force --ignore-daemonsets --grace-period 30 --delete-local-data {{ ansible_hostname }}"
   delegate_to: "{{ groups['kube-master'][0] }}"
 
 - name: Sleep for grace period for draining