Don't create "admin" group

According to the Ubuntu 12.04 release notes, up until Ubuntu 11.10
admin access was granted via the "admin" unix group, but was changed
to the "sudo" group to be more consistent with Debian et al.

Remove the now unnecessary group

Modify the install-ansible role to set some directory ownership to
root:root; there didn't seem to be any reason to use admin here.

This means the "users" role is no longer required in the bridge.yaml,
as it is run from the base playbook anyway.

Change-Id: I6a7fdd460fb472f0d3468eb080aebbb010931e11

playbooks/bridge.yaml

@@ -1,7 +1,6 @@
 - hosts: bridge.openstack.org
   become: true
   roles:
-    - users
     - pip3
     - install-ansible
     - root-keys

playbooks/roles/install-ansible/tasks/main.yaml

@@ -21,7 +21,7 @@
     state: directory
     path: /var/cache/ansible
     owner: root
-    group: admin
+    group: root
     mode: 0770
 
 - name: Ensure ansible log dir is writable
@@ -29,7 +29,7 @@
     path: /var/log/ansible
     state: directory
     owner: root
-    group: admin
+    group: root
     mode: 0775
 
 - name: Copy ansible.cfg in to place

playbooks/roles/users/tasks/main.yaml

@@ -1,11 +1,7 @@
-- name: Add sudo admin groups
+- name: Add sudo group
-  loop:
-    - sudo
-    - admin
   group:
-    name: "{{ item }}"
+    name: "sudo"
     state: present
-  when:
 
 # NOTE(mordred): We replace the main file rather than dropping a file in to
 # /etc/sudoers.d to deal with divergent base sudoers files from our distros.
@@ -52,7 +48,7 @@
     uid: "{{ all_users[item].uid }}"
     group: "{{ item }}"
     comment: "{{ all_users[item].comment }}"
-    groups: admin,sudo
+    groups: sudo
     shell: /bin/bash
   when:
     - item in all_users