Added notion of a general Store abstraction and wired it up in ClusterStore.
diff --git a/core/api/src/main/java/org/onlab/onos/store/StoreDelegate.java b/core/api/src/main/java/org/onlab/onos/store/StoreDelegate.java
new file mode 100644
index 0000000..e2c5cd3
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/store/StoreDelegate.java
@@ -0,0 +1,13 @@
+package org.onlab.onos.store;
+
+import org.onlab.onos.event.Event;
+
+/**
+ * Entity associated with a store and capable of receiving notifications of
+ * events within the store.
+ */
+public interface StoreDelegate<E extends Event> {
+
+ void notify(E event);
+
+}