Release RocksDB 4.0.0

Summary: Release RocksDB 4.0.0

Test Plan: no test

Reviewers: sdong, yhchiang, anthony, rven, kradhakrishnan, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46515

HISTORY.md

 # Rocksdb Change Log
 
-## Unreleased
-
+## 4.0.0 (9/9/2015)
 ### New Features
 * Added support for transactions.  See include/rocksdb/utilities/transaction.h for more info.
 * DB::GetProperty() now accept "rocksdb.aggregated-table-properties" and "rocksdb.aggregated-table-properties-at-levelN", in which case it returns aggregated table properties of the target column family, or the aggregated table properties of the specified level N if the "at-level" version is used.

include/rocksdb/version.h

@@ -4,8 +4,8 @@
 // of patent rights can be found in the PATENTS file in the same directory.
 #pragma once
 
-#define ROCKSDB_MAJOR 3
-#define ROCKSDB_MINOR 14
+#define ROCKSDB_MAJOR 4
+#define ROCKSDB_MINOR 0
 #define ROCKSDB_PATCH 0
 
 // Do not use these. We made the mistake of declaring macros starting with