auth: update LICENSE header

auth/simple_token.go

@@ -1,4 +1,4 @@
-// Copyright 2016 Nippon Telegraph and Telephone Corporation.
+// Copyright 2016 The etcd Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

auth/store.go

@@ -1,4 +1,4 @@
-// Copyright 2016 Nippon Telegraph and Telephone Corporation.
+// Copyright 2016 The etcd Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

auth/store_test.go

@@ -1,4 +1,4 @@
-// Copyright 2016 CoreOS, Inc.
+// Copyright 2016 The etcd Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.