Update copyright notice from Swarming to LUCI; add AUTHORS and CONTRIBUTORS.

- The LUCI Authors is a strict superset of the Swarming Authors.
- Add CONTRIBUTORS with the exact list of contributors.
- Fix a long standing discrepency between the copyright notice in appengine/ and
  in client/.
- The vast majority of this CL was created with sed. The only files modified
  manually are:
  - AUTHORS
  - CONTRIBUTORS
  - LICENSE
  - PRESUBMIT.py
  - appengine/PRESUBMIT.py (deleted)
  - client/LICENSE
  - client/PRESUBMIT.py

R=vadimsh@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1860863002

Cr-Mirrored-From: https://github.com/luci/luci-py
Cr-Mirrored-Commit: 8e594074929871a9761d27e814541bc0d7d84744
diff --git a/utils/logging_utils.py b/utils/logging_utils.py
index e824ad4..c908233 100644
--- a/utils/logging_utils.py
+++ b/utils/logging_utils.py
@@ -1,6 +1,6 @@
-# Copyright 2015 The Swarming Authors. All rights reserved.
-# Use of this source code is governed under the Apache License, Version 2.0 that
-# can be found in the LICENSE file.
+# Copyright 2015 The LUCI Authors. All rights reserved.
+# Use of this source code is governed by the Apache v2.0 license that can be
+# found in the LICENSE file.
 
 """Utility relating to logging."""