Release RocksDB 5.5.0

Summary:
change history.md and version
Closes https://github.com/facebook/rocksdb/pull/2317

Differential Revision: D5080484

Pulled By: lightmark

fbshipit-source-id: 8d70b3b52dc0d34fefc0d34f91d379c27ac13ed3

HISTORY.md

@@ -1,5 +1,7 @@
 # Rocksdb Change Log
 ## Unreleased
+
+## 5.5.0 (05/17/2017)
 ### New Features
 * FIFO compaction to support Intra L0 compaction too with CompactionOptionsFIFO.allow_compaction=true.
 * DB::ResetStats() to reset internal stats.
@@ -9,6 +11,8 @@
 * Support dynamically change `max_open_files` option via SetDBOptions()
 * Added DB::CreateColumnFamilie() and DB::DropColumnFamilies() to bulk create/drop column families.
 * Add debugging function `GetAllKeyVersions` to see internal versions of a range of keys.
+* Support file ingestion with universal compaction style
+* Support file ingestion behind with option `allow_ingest_behind`
 
 ## 5.4.0 (04/11/2017)
 ### Public API Change

include/rocksdb/version.h

@@ -5,7 +5,7 @@
 #pragma once
 
 #define ROCKSDB_MAJOR 5
-#define ROCKSDB_MINOR 4
+#define ROCKSDB_MINOR 5
 #define ROCKSDB_PATCH 0
 
 // Do not use these. We made the mistake of declaring macros starting with