Added creationTime to Versioned object. This enables supporting a electedTime in leadership, which in turn helps us track how stable leadership terms are.

Change-Id: Ib051027625324646152ed85535ba337e95f8a061
diff --git a/core/store/trivial/src/main/java/org/onosproject/store/trivial/impl/SimpleLeadershipManager.java b/core/store/trivial/src/main/java/org/onosproject/store/trivial/impl/SimpleLeadershipManager.java
index d61772e..35654f2 100644
--- a/core/store/trivial/src/main/java/org/onosproject/store/trivial/impl/SimpleLeadershipManager.java
+++ b/core/store/trivial/src/main/java/org/onosproject/store/trivial/impl/SimpleLeadershipManager.java
@@ -61,7 +61,7 @@
     @Override
     public Leadership getLeadership(String path) {
         checkArgument(path != null);
-        return elections.get(path) ? new Leadership(path, clusterService.getLocalNode().id(), 0) : null;
+        return elections.get(path) ? new Leadership(path, clusterService.getLocalNode().id(), 0, 0) : null;
     }
 
     @Override
@@ -79,7 +79,7 @@
         elections.put(path, true);
         for (LeadershipEventListener listener : listeners) {
             listener.event(new LeadershipEvent(Type.LEADER_ELECTED,
-                    new Leadership(path, clusterService.getLocalNode().id(), 0)));
+                    new Leadership(path, clusterService.getLocalNode().id(), 0, 0)));
         }
     }
 
@@ -88,7 +88,7 @@
         elections.remove(path);
         for (LeadershipEventListener listener : listeners) {
             listener.event(new LeadershipEvent(Type.LEADER_BOOTED,
-                    new Leadership(path, clusterService.getLocalNode().id(), 0)));
+                    new Leadership(path, clusterService.getLocalNode().id(), 0, 0)));
         }
     }