Extend check_gateway script

ensure that dhcp server is stopped or started depending on gw mode

files/usr/local/bin/check_gateway

@@ -31,4 +31,21 @@ OLD_STATE="$(cat $MESH/gw_mode)"
         # Restart DHCP server
         /usr/sbin/service isc-dhcp-server start
     fi
+    exit 0
 done
+
+if [ "$NEW_STATE" == "server" ]; then
+    /usr/sbin/service isc-dhcp-server status 2>&1> /dev/null
+    if [[ $? -ne 0 ]]
+    then
+        /usr/sbin/service isc-dhcp-server restart
+    fi
+fi
+if [ "$NEW_STATE" == "off" ]; then
+    /usr/sbin/service isc-dhcp-server status 2>&1> /dev/null
+    if [[ $? -eq 0 ]]
+    then
+        /usr/sbin/service isc-dhcp-server stop
+    fi
+fi
+