Fix importing config module and classmethod params

The Token/Endpoint options specify an instance method where the
expectation is a classmethod. This prevents the class being loaded from
config file or CLI.

The cfg module was not imported so loading plugins would raise an
AttributeError.

Change-Id: I33b4a8c181210d74d4779438afc1f918e06df85b

keystoneclient/auth/token_endpoint.py

@@ -10,6 +10,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from oslo.config import cfg
 
 from keystoneclient.auth import base
 
@@ -38,8 +39,9 @@ class Token(base.BaseAuthPlugin):
         """
         return self.endpoint
 
-    def get_options(self):
-        options = super(Token, self).get_options()
+    @classmethod
+    def get_options(cls):
+        options = super(Token, cls).get_options()
 
         options.extend([
             cfg.StrOpt('endpoint',

keystoneclient/tests/auth/test_token_endpoint.py

@@ -10,6 +10,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+from testtools import matchers
+
 from keystoneclient.auth import token_endpoint
 from keystoneclient import session
 from keystoneclient.tests import utils
@@ -43,3 +45,11 @@ class TokenEndpointTest(utils.TestCase):
         self.assertEqual(self.TEST_URL, a.get_endpoint(s))
         self.assertEqual('body', data.text)
         self.assertRequestHeaderEqual('X-Auth-Token', self.TEST_TOKEN)
+
+    def test_token_endpoint_options(self):
+        opt_names = [opt.name for opt in token_endpoint.Token.get_options()]
+
+        self.assertThat(opt_names, matchers.HasLength(2))
+
+        self.assertIn('token', opt_names)
+        self.assertIn('endpoint', opt_names)