Added top-level location object per Simon/Paul spec.
Fixed an NPE in mastership when running optical demo.

Change-Id: I038000d1237b4150db0c722fa96dd9541d83e44e
diff --git a/web/gui/src/main/webapp/json/of_0000000000000004.json b/web/gui/src/main/webapp/json/of_0000000000000004.json
index f3f2132..ba243baf 100644
--- a/web/gui/src/main/webapp/json/of_0000000000000004.json
+++ b/web/gui/src/main/webapp/json/of_0000000000000004.json
@@ -3,6 +3,11 @@
     "id": "of:0000000000000004",
     "type": "switch",
     "propOrder": [ "name", "type", "dpid", "latitude", "longitude", "allowed" ],
+    "location": {
+        "type": "latlng",
+        "lat": 32.8,
+        "lng": 117.1
+    },
     "props": {
         "allowed": true,
         "latitude": 32.8,