Update HISTORY and version for upcoming 5.14

Summary: Closes https://github.com/facebook/rocksdb/pull/3866

Differential Revision: D8043563

Pulled By: gfosco

fbshipit-source-id: da4af20e604534602ac0e07943135513fd9a9f53

HISTORY.md

 # Rocksdb Change Log
 ## Unreleased
+
+## 5.14.0 (5/16/2018)
 ### Public API Change
 * Add a BlockBasedTableOption to align uncompressed data blocks on the smaller of block size or page size boundary, to reduce flash reads by avoiding reads spanning 4K pages.
 * The background thread naming convention changed (on supporting platforms) to "rocksdb:<thread pool priority><thread number>", e.g., "rocksdb:low0".

include/rocksdb/version.h

@@ -5,7 +5,7 @@
 #pragma once
 
 #define ROCKSDB_MAJOR 5
-#define ROCKSDB_MINOR 13
+#define ROCKSDB_MINOR 14
 #define ROCKSDB_PATCH 0
 
 // Do not use these. We made the mistake of declaring macros starting with