Remove usage of six

With python3.x, classes can use 'metaclass=' instead of
'six.add_metaclass', 'six.iteritems' and 'six.iterkeys' can
be replaced by 'items' and 'keys', 'six.moves.urllib.parse'
can be replaced by 'urllib.parse', 'six.StringIO' and
'six.moves.cStringIO' can be replaced by 'io.StringIO',
'six.text_type' and 'six.string_type' are just 'str'.

Change-Id: I84848c0bf8ab3c36dd821141191e2725e4e3b58b

openstackclient/api/object_store_v1.py

@@ -17,9 +17,9 @@ import io
 import logging
 import os
 import sys
+import urllib
 
 from osc_lib import utils
-from six.moves import urllib
 
 from openstackclient.api import api