make interface route gw not mandatory

Change-Id: If2d31176d28d85c7d13cc44f34f923a821942f46

linux/network/interface.sls

@@ -301,7 +301,9 @@ linux_network_{{ interface_name }}_routes:
     - name: {{ route_name }}
       ipaddr: {{ route.address }}
       netmask: {{ route.netmask }}
+      {%- if route.gateway is defined %}
       gateway: {{ route.gateway }}
+      {%- endif %}
     {%- endfor %}
 
 {%- endif %}

tests/pillar/network_extended.sls

@@ -0,0 +1,34 @@
+linux:
+  system:
+    enabled: true
+    domain: ci.local
+    name: linux
+  network:
+    enabled: true
+    hostname: linux
+    fqdn: linux.ci.local
+    network_manager: false
+    interface:
+      eth0:
+        enabled: true
+        type: eth
+        address: 192.168.0.102
+        netmask: 255.255.255.0
+        gateway: 192.168.0.1
+        name_servers:
+        - 8.8.8.8
+        - 8.8.4.4
+        mtu: 1500
+        route:
+          kubernetes_internal:
+            address: 10.254.0.0
+            netmask: 255.255.0.0
+          some_other:
+            address: 10.111.0.0
+            netmask: 255.255.0.0
+            gateway: 1.1.1.1
+      vlan69:
+        enabled: true
+        type: vlan
+        use_interfaces:
+        - interface: ${linux:interface:eth0}