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

appengine/swarming/mapreduce_jobs.py

-# Copyright 2014 The Swarming Authors. All rights reserved.
+# Copyright 2014 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.
 
 """Defines the mapreduces, which are used to do one-off mass updates on entities
 and other manually triggered maintenance tasks.
 
 Automatically triggered maintenance tasks should use a task queue on the backend
 instead.
 """
 
@@ skipping 201 matching lines @@
       the task, each one individually encoded as a JSON string.
   """
   for labels_json in labels_json_list:
     try:
       labels = json.loads(labels_json)
       logging.info('Reducing %s: %s', test_name,
                    json.dumps(labels, indent=2, separators=(',', ': ')))
       # TODO(smut): Do something with this information. Store it somewhere.
     except (IOError, ValueError):
       logging.error('Invalid labels for %s: %s', test_name, labels_json)