Don't add sudo group by default.

This formula doesn't really require the sudo group (unless
there are actually users in that group). Moreover, on FreeBSD
the 'admin' group would be wheel and not sudo.

users/init.sls

 
 {% for group in user.get('groups', []) %}
 users_{{ name }}_{{ group }}_group:
-  group:
+  group.present:
     - name: {{ group }}
-    - present
+    {% if group == 'sudo' %}
+    - system: True
+    {% endif %}
 {% endfor %}
 
 users_{{ name }}_user:

users/sudo.sls

   pkg.installed:
     - name: {{ users.bash_package }}
 
-users_sudo-group:
-  group.present:
-    - name: sudo
-    - system: True
-
 users_sudo-package:
   pkg.installed:
     - name: {{ users.sudo_package }}
     - require:
-      - group: users_sudo-group
       - file: {{ users.sudoers_dir }} 
 
 users_{{ users.sudoers_dir }}: