Prepare 3.12

Summary: About to cut release

Test Plan: none

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D41061

HISTORY.md

@@ -1,5 +1,6 @@
 # Rocksdb Change Log
 
+## 3.12.0 (7/2/2015)
 ### New Features
 * Added experimental support for optimistic transactions.  See include/rocksdb/utilities/optimistic_transaction.h for more info.
 * Added a new way to report QPS from db_bench (check out --report_file and --report_interval_seconds)

include/rocksdb/version.h

@@ -5,7 +5,7 @@
 #pragma once
 
 #define ROCKSDB_MAJOR 3
-#define ROCKSDB_MINOR 11
+#define ROCKSDB_MINOR 12
 #define ROCKSDB_PATCH 0
 
 // Do not use these. We made the mistake of declaring macros starting with