Added notion of a general Store abstraction and wired it up in ClusterStore.
diff --git a/core/store/src/main/java/org/onlab/onos/store/common/package-info.java b/core/store/src/main/java/org/onlab/onos/store/common/package-info.java
new file mode 100644
index 0000000..cf19812
--- /dev/null
+++ b/core/store/src/main/java/org/onlab/onos/store/common/package-info.java
@@ -0,0 +1,5 @@
+/**
+ * Common abstractions and facilities for implementing distributed store
+ * using Hazelcast.
+ */
+package org.onlab.onos.store.common;