Add tags to deploy components by --tags option (#2960)

* Add tags for cert serial tasks

This will help facilitate tag-based deployment of specific components.

* fixup kubernetes node

roles/etcd/tasks/main.yml

@@ -19,11 +19,17 @@
   register: "etcd_client_cert_serial_result"
   changed_when: false
   when: inventory_hostname in groups['k8s-cluster']|union(groups['etcd'])|union(groups['calico-rr']|default([]))|unique|sort
+  tags:
+    - master
+    - network
 
 - name: Set etcd_client_cert_serial
   set_fact:
     etcd_client_cert_serial: "{{ etcd_client_cert_serial_result.stdout }}"
   when: inventory_hostname in groups['k8s-cluster']|union(groups['etcd'])|union(groups['calico-rr']|default([]))|unique|sort
+  tags:
+    - master
+    - network
 
 - include_tasks: "install_{{ etcd_deployment_type }}.yml"
   when: is_etcd_master