Install dhcp-server on nodes with role 'batman_gw'.

Signed-off-by: Maximilian Wilhelm <max@rfc2324.org>

top.sls

@@ -34,11 +34,16 @@ base:
     - match: pillar
     - bird
 
-  # Batman node?
+  # Batman node
   nodes:{{ grains['id'] }}:roles:batman:
     - match: pillar
     - batman
 
+  # Batman gateway
+  nodes:{{ grains['id'] }}:roles:batman_gw:
+    - match: pillar
+    - dhcp-server
+
   # BRAS / Fastd
   nodes:{{ grains['id'] }}:roles:fastd:
     - match: pillar