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

client/utils/file_path.py

-# Copyright 2013 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 2013 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.
 
 """Provides functions: get_native_path_case(), isabs() and safe_join().
 
 This module assumes that filesystem is not changing while current process
 is running and thus it caches results of functions that depend on FS state.
 """
 
 import ctypes
 import getpass
 import logging
@@ skipping 957 matching lines @@
   errors = []
   fs.rmtree(root, onerror=lambda *args: errors.append(args))
   if errors:
     # There's no hope.
     sys.stderr.write(
         'Failed to delete %s. The following files remain:\n' % root)
     for _, path, _ in errors:
       sys.stderr.write('- %s\n' % path)
     raise errors[0][2][0], errors[0][2][1], errors[0][2][2]
   return False