tablet-leader command to check current Raft leader

Change-Id: Id360db21988a50c3e2895c5194d59b0ba4cb49e4
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseClient.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseClient.java
index 17f356b..2e06696 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseClient.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseClient.java
@@ -151,4 +151,8 @@
     public Map<String, VersionedValue> getAll(String tableName) {
         return submit("getAll", tableName);
     }
+
+    Member getCurrentLeader() {
+        return currentLeader;
+    }
 }