Normalize tags in all places to prepare for tag fixing in future (#1739)

roles/docker/tasks/main.yml

@@ -12,11 +12,13 @@
       paths:
         - ../vars
       skip: true
-  tags: facts
+  tags:
+    - facts
 
 - include: set_facts_dns.yml
   when: dns_mode != 'none' and resolvconf_mode == 'docker_dns'
-  tags: facts
+  tags:
+    - facts
 
 - name: check for minimum kernel version
   fail:
@@ -25,7 +27,8 @@
           {{ docker_kernel_min_version }} on
           {{ ansible_distribution }}-{{ ansible_distribution_version }}
   when: (not ansible_os_family in ["CoreOS", "Container Linux by CoreOS"]) and (ansible_kernel|version_compare(docker_kernel_min_version, "<"))
-  tags: facts
+  tags:
+    - facts
 
 - name: ensure docker repository public key is installed
   action: "{{ docker_repo_key_info.pkg_key }}"