Remove usage of six

Remove six-library Replace the following items with Python 3 style code.
- six.add_metaclass

Change-Id: I7da3e8898e00bc07f6e462cbc9765ce7c199faa2

tempest/lib/auth.py

@@ -21,7 +21,6 @@ import re
 from urllib import parse as urlparse
 
 from oslo_log import log as logging
-import six
 
 from tempest.lib import exceptions
 from tempest.lib.services.identity.v2 import token_client as json_v2id
@@ -65,8 +64,7 @@ def apply_url_filters(url, filters):
     return url
 
 
-@six.add_metaclass(abc.ABCMeta)
-class AuthProvider(object):
+class AuthProvider(object, metaclass=abc.ABCMeta):
     """Provide authentication"""
 
     SCOPES = set(['project'])

tempest/lib/common/cred_client.py

@@ -13,7 +13,6 @@
 import abc
 
 from oslo_log import log as logging
-import six
 
 from tempest.lib import auth
 from tempest.lib import exceptions as lib_exc
@@ -22,8 +21,7 @@ from tempest.lib.services.identity.v2 import identity_client as v2_identity
 LOG = logging.getLogger(__name__)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class CredsClient(object):
+class CredsClient(object, metaclass=abc.ABCMeta):
     """This class is a wrapper around the identity clients
 
      to provide a single interface for managing credentials in both v2 and v3

tempest/lib/common/cred_provider.py

@@ -14,14 +14,12 @@
 
 import abc
 
-import six
 
 from tempest.lib import auth
 from tempest.lib import exceptions
 
 
-@six.add_metaclass(abc.ABCMeta)
-class CredentialProvider(object):
+class CredentialProvider(object, metaclass=abc.ABCMeta):
     def __init__(self, identity_version, name=None,
                  network_resources=None, credentials_domain=None,
                  admin_role=None, identity_uri=None):

tempest/test_discover/plugins.py

@@ -15,7 +15,6 @@
 import abc
 
 from oslo_log import log as logging
-import six
 import stevedore
 
 from tempest.lib.common.utils import misc
@@ -24,8 +23,7 @@ from tempest.lib.services import clients
 LOG = logging.getLogger(__name__)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class TempestPlugin(object):
+class TempestPlugin(object, metaclass=abc.ABCMeta):
     """Provide basic hooks for an external plugin
 
     To provide tempest the necessary information to run the plugin.

tempest/tests/lib/test_decorators.py

@@ -16,7 +16,6 @@
 import abc
 from unittest import mock
 
-import six
 import testtools
 
 from tempest.lib import base as test
@@ -69,8 +68,7 @@ class TestAttrDecorator(base.TestCase):
                                condition=True)
 
 
-@six.add_metaclass(abc.ABCMeta)
-class BaseSkipDecoratorTests(object):
+class BaseSkipDecoratorTests(object, metaclass=abc.ABCMeta):
 
     @abc.abstractmethod
     def _test_skip_helper(self, raise_exception=True, expected_to_skip=True,