Implement Atomix AsyncAtomicCounterMap, AtomicCounterMap and state machine.

Change-Id: Ifd7f60ae8dcfe7239e034a92654b4ef30ffe46ae
diff --git a/core/api/src/main/java/org/onosproject/store/service/StorageService.java b/core/api/src/main/java/org/onosproject/store/service/StorageService.java
index d532be2..e034e57 100644
--- a/core/api/src/main/java/org/onosproject/store/service/StorageService.java
+++ b/core/api/src/main/java/org/onosproject/store/service/StorageService.java
@@ -69,6 +69,14 @@
     <K, V> ConsistentMultimapBuilder<K, V> consistentMultimapBuilder();
 
     /**
+     * Creates a new {@code AtomicCounterMapBuilder}.
+     *
+     * @param <K> key type
+     * @return builder for an atomic counter map
+     */
+    <K> AtomicCounterMapBuilder<K> atomicCounterMapBuilder();
+
+    /**
      * Creates a new DistributedSetBuilder.
      *
      * @param <E> set element type