change gid_from_name to false to user present

saltstack 2017.7 is failing to create user when default group for user is not present, commit which changes this behavior from 2016.3 is a18dbe0c11

Change-Id: I478d632e8aa7303ab2ee32b033478148c18c473d

linux/system/user.sls

@@ -29,7 +29,7 @@ system_user_{{ name }}:
   - password: {{ user.password }}
   - hash_password: {{ user.get('hash_password', False) }}
   {% endif %}
-  - gid_from_name: true
+  - gid_from_name: false
   {%- if user.groups is defined %}
   - groups: {{ user.groups }}
   {%- endif %}