Simpler way to construct MapDBLog
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/MapDBLog.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/MapDBLog.java
index 893c311..b7165c3 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/MapDBLog.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/MapDBLog.java
@@ -35,8 +35,8 @@
     private static final String LOG_NAME = "log";
     private static final String SIZE_FIELD_NAME = "size";
 
-    public MapDBLog(File dbFile, StoreSerializer serializer) {
-        this.dbFile = dbFile;
+    public MapDBLog(String dbFileName, StoreSerializer serializer) {
+        this.dbFile = new File(dbFileName);
         this.serializer = serializer;
     }
 
@@ -277,4 +277,4 @@
             }
         });
     }
-}
\ No newline at end of file
+}