Encrypt Postgres passwords, and fix change-reporting.

roles/mailserver/tasks/postfix.yml

   tags:
     - dependencies
 
-- name: Set postgres password
-  command: sudo -u {{ db_admin_username }} psql -d {{ db_admin_username }} -c "ALTER USER postgres with  password '{{ db_admin_password }}';"
+- name: Set postgres user password
+  become: true
+  become_user: postgres
+  postgresql_user: name={{ db_admin_username }} password={{ db_admin_password }} encrypted=yes
   notify: import sql postfix
 
 - name: Create database user for mail server
-  postgresql_user: login_host=localhost login_user={{ db_admin_username }} login_password="{{ db_admin_password }}" name={{ mail_db_username }} password="{{ mail_db_password }}" state=present
+  postgresql_user: login_host=localhost login_user={{ db_admin_username }} login_password="{{ db_admin_password }}" name={{ mail_db_username }} password="{{ mail_db_password }}" encrypted=yes state=present
   notify: import sql postfix
 
 - name: Create database for mail server