Fix flake8 issues

Signed-off-by: Christophe Labouisse <christophe@labouisse.org>

docker/client.py

@@ -18,13 +18,12 @@ import re
 import shlex
 import struct
 import warnings
+from datetime import datetime
 
 import requests
 import requests.exceptions
 import six
 
-from datetime import datetime
-
 from .auth import auth
 from .unixconn import unixconn
 from .ssladapter import ssladapter
@@ -32,6 +31,7 @@ from .utils import utils
 from . import errors
 from .tls import TLSConfig
 
+
 if not six.PY3:
     import websocket