Intents are now removed after being withdrawn.

Change-Id: I7574fe94add00abf58c71c6122bb3dc5aafa0f79
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentManager.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentManager.java
index fb6aa40..da2fe70 100644
--- a/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentManager.java
+++ b/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentManager.java
@@ -694,6 +694,10 @@
             if (event != null) {
                 eventDispatcher.post(event);
             }
+
+            if (newState == WITHDRAWN) {
+                store.removeIntent(intent.id());
+            }
         }
 
         Map<Intent, IntentState> stateMap() {