bug in log handler record handling

From #144, an odd error is manifesting with our log handler attempting to parse a log record.

2018-03-08 00:14:15,695 - MainThread - botocore.vendored.requests.packages.urllib3.connectionpool - INFO - Starting new HTTPS connection (1): kms.ap-southeast-2.amazonaws.com
Traceback (most recent call last):
  File "/usr/lib64/python2.7/logging/__init__.py", line 851, in emit
    msg = self.format(record)
  File "/usr/lib64/python2.7/logging/__init__.py", line 724, in format
    return fmt.format(record)
  File "/usr/lib/python2.7/site-packages/aws_encryption_sdk_cli/internal/logging_utils.py", line 137, in format
    _record = self.__redact_record(record)
  File "/usr/lib/python2.7/site-packages/aws_encryption_sdk_cli/internal/logging_utils.py", line 123, in __redact_record
    _record = copy.deepcopy(record)
  File "/usr/lib64/python2.7/copy.py", line 190, in deepcopy
    y = _reconstruct(x, rv, 1, memo)
  File "/usr/lib64/python2.7/copy.py", line 334, in _reconstruct
    state = deepcopy(state, memo)
  File "/usr/lib64/python2.7/copy.py", line 163, in deepcopy
    y = copier(x, memo)
  File "/usr/lib64/python2.7/copy.py", line 257, in _deepcopy_dict
    y[deepcopy(key, memo)] = deepcopy(value, memo)
  File "/usr/lib64/python2.7/copy.py", line 163, in deepcopy
    y = copier(x, memo)
  File "/usr/lib64/python2.7/copy.py", line 237, in _deepcopy_tuple
    y.append(deepcopy(a, memo))
  File "/usr/lib64/python2.7/copy.py", line 190, in deepcopy
    y = _reconstruct(x, rv, 1, memo)
  File "/usr/lib64/python2.7/copy.py", line 329, in _reconstruct
    y = callable(*args)
TypeError: __init__() takes exactly 3 arguments (2 given)