update year in LICENSE, conf.py and README.md files

I found that year in files is not up-to-date

LICENSE

@@ -1,9 +1,9 @@
-Copyright (c) 2014 by Contributors 
+Copyright (c) 2016 by Contributors
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
-    
+
    http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software

README.md

@@ -41,7 +41,7 @@ XGBoost has been developed and used by a group of active community members. Your
 
 License
 -------
-© Contributors, 2015. Licensed under an [Apache-2](https://github.com/dmlc/xgboost/blob/master/LICENSE) license.
+© Contributors, 2016. Licensed under an [Apache-2](https://github.com/dmlc/xgboost/blob/master/LICENSE) license.
 
 
 Reference

doc/conf.py

@@ -35,7 +35,7 @@ for mod_name in MOCK_MODULES:
 # General information about the project.
 project = u'xgboost'
 author = u'%s developers' % project
-copyright = u'2015, %s' % author
+copyright = u'2016, %s' % author
 github_doc_root = 'https://github.com/dmlc/xgboost/tree/master/doc/'
 
 # add markdown parser