Add NOTICE file from original steno repository

Apache 2.0 license requires distributing the NOTICE file along with
LICENSE for proper attribution. This file contains copyright notices
for the original steno project.

Author: johha

lib/steno/NOTICE

@@ -0,0 +1,14 @@
+Steno
+
+Copyright (c) 2015 - Present CloudFoundry.org Foundation, Inc. All Rights Reserved.
+
+This project contains software that is Copyright (c) 2012-2015 Pivotal Software, Inc.
+
+Other copyright notices for portions of this software are listed in the LICENSE file. 
+
+This product is licensed to you under the Apache License, Version 2.0 (the "License").  
+You may not use this product except in compliance with the License.  
+
+This product may include a number of subcomponents with separate copyright notices 
+and license terms. Your use of these subcomponents is subject to the terms and 
+conditions of the subcomponent's license, as noted in the LICENSE file.

lib/steno/STENO_HISTORY.md

@@ -123,6 +123,7 @@ a1a602a Initial commit of steno
 - All steno library code (~1,106 lines)
 - Custom RFC3339 codec (previously in lib/steno_custom_codec_temp/)
 - LICENSE file (Apache 2.0 - copied from original repository for attribution)
+- NOTICE file (Apache 2.0 copyright notices - copied from original repository)
 - Test suite (moved to spec/unit/lib/steno/)
 
 ## What Was Excluded