Use common_timezone and fix idempotence

Thanks-to: 8e693b3db3

roles/common/tasks/main.yml

   tags:
     - dependencies
 
-- name: Set timezone to UTC
-  action: shell echo Etc/UTC > /etc/timezone
+- name: timezone - configure /etc/timezone
+  copy:
+    content: "{{ common_timezone | regex_replace('$', '\n') }}"
+    dest: /etc/timezone
+    owner: root
+    group: root
+    mode: 0644
+  register: common_timezone_config
 
-- name: Set localtime to UTC
+- name: timezone - Set localtime to UTC
   file: src=/usr/share/zoneinfo/Etc/UTC dest=/etc/localtime
+  when: common_timezone_config.changed
 
-- name: Reconfigure tzdata
-  action: command dpkg-reconfigure -f noninteractive tzdata
-  when: ansible_distribution == 'Debian' or ansible_distribution == 'Ubuntu'
+- name: timezone - reconfigure tzdata
+  command: dpkg-reconfigure --frontend noninteractive tzdata
+  when: common_timezone_config.changed
 
 - name: Apticron email configuration
   template: src=apticron.conf.j2 dest=/etc/apticron/apticron.conf

vars/defaults.yml

 ###############################################################################
 
 # # common
+# common_timezone: 'Etc/UTC' (required)
 # domain: (required)
 # main_user_name: (required)
 admin_email: "{{ main_user_name }}@{{ domain }}"

vars/testing.yml

 ###############################################################################
 
 # common
+common_timezone: 'Etc/UTC'
 domain: sovereign.local
 main_user_name: sovereign
 encfs_password: testPassword

vars/user.yml

 ###############################################################################
 
 # common
+common_timezone: 'Etc/UTC'
 domain: TODO.com
 main_user_name: TODO
 encfs_password: TODO    # NOTE: must not contain dollar sign characters '$'