Adding a grid topology simulator to the null provider.

Change-Id: Ie655840febc11d3986f1c8ec5c8ef2374014794c
diff --git a/providers/null/src/main/java/org/onosproject/provider/nil/cli/TopologyShapeCompleter.java b/providers/null/src/main/java/org/onosproject/provider/nil/cli/TopologyShapeCompleter.java
index fad29b6..dbb386d 100644
--- a/providers/null/src/main/java/org/onosproject/provider/nil/cli/TopologyShapeCompleter.java
+++ b/providers/null/src/main/java/org/onosproject/provider/nil/cli/TopologyShapeCompleter.java
@@ -27,6 +27,6 @@
     @Override
     public List<String> choices() {
         return ImmutableList.of("configured", "linear", "reroute", "centipede",
-                                "tree", "spineleaf", "mesh");
+                                "tree", "spineleaf", "mesh", "grid");
     }
 }