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

appengine/swarming/swarming_bot/bot_code/singleton_test.py

 #!/usr/bin/env python
-# Copyright 2015 The Swarming Authors. All rights reserved.
+# 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.
 
 import logging
 import os
 import subprocess
 import sys
 import threading
 import unittest
 
@@ skipping 39 matching lines @@
     self.assertEqual('True\n', subprocess.check_output(CMD_ACQUIRE))
 
 
 if __name__ == '__main__':
   os.chdir(THIS_DIR)
   if '-v' in sys.argv:
     unittest.TestCase.maxDiff = None
   logging.basicConfig(
       level=logging.DEBUG if '-v' in sys.argv else logging.CRITICAL)
   unittest.main()