fix for issue #134 - compatibly issues in grub configuration with RedHat os_family systems

linux/system/grub.sls

     - mode: 755
     - makedirs: True
 
+{%- if grains['os_family'] == 'RedHat' %}
+/etc/default/grub:
+  file.append:
+    - text:
+      - for i in $(ls /etc/default/grub.d);do source /etc/default/grub.d/$i ;done
+
+grub_update:
+  cmd.wait:
+  - name: grub2-mkconfig -o /boot/grub2/grub.cfg
+
+{%- else %}
+
 {%- if grains.get('virtual_subtype', None) not in ['Docker', 'LXC'] %}
 grub_update:
   cmd.wait:
   - name: update-grub
 {%- endif %}
+
+{%- endif %}