Misc fixes/improvments to ECMapImpl. Most notably:
- Fixed logic in determining random peer to do AE
- Fixed for logic for when to do active sync if lightWeightAE is disabled
- Fixed tracking of ECMap activity

Change-Id: I35da91d6ef684e16630be7bd5e518c8400debe14
diff --git a/core/store/dist/src/main/java/org/onosproject/store/ecmap/PersistentStore.java b/core/store/dist/src/main/java/org/onosproject/store/ecmap/PersistentStore.java
index 302f7f8..e85987a 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/ecmap/PersistentStore.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/ecmap/PersistentStore.java
@@ -37,4 +37,11 @@
      * @param value the value
      */
     void update(K key, MapValue<V> value);
+
+    /**
+     * Removes a key from persistent store.
+     *
+     * @param key the key to remove
+     */
+    void remove(K key);
 }