Include linux.system.group when needed

Change-Id: I2163dbdee38e1b9c5c4dec6611550f16fdf1373b

linux/system/user.sls

 {%- from "linux/map.jinja" import system with context %}
 {%- if system.enabled %}
 
+include:
+  - linux.system.group
+
 {%- for name, user in system.user.iteritems() %}
 
 {%- if user.enabled %}
   {%- endif %}
 {%- endfor %}
 
-
 system_user_{{ name }}:
   user.present:
   - name: {{ name }}

tests/pillar/system.sls

         enabled: true
         home: /root
         name: root
-      test:
+      testuser:
         enabled: true
-        name: test
+        name: testuser
         sudo: true
         uid: 9999
         full_name: Test User
         groups:
           - sudogroup1
     group:
-      test:
+      testgroup:
         enabled: true
-        name: test
+        name: testgroup
         gid: 9999
         system: true
       db-ops:
       test:
         enabled: true
         command: "/bin/sleep 3"
-        user: test
+        user: testuser
         minute: 0
         hour: 13
     package: