assertEquals is deprecated, use assertEqual

assertEquals is deprecated in Python 2.7 , need drop it
http://docs.python.org/2/library/unittest.html#deprecated-aliases

Change-Id: I05061251efe1ea840dd9741d254babcf0f565068
diff --git a/tempest/api/identity/admin/test_roles.py b/tempest/api/identity/admin/test_roles.py
index ac145c6..c234efd 100644
--- a/tempest/api/identity/admin/test_roles.py
+++ b/tempest/api/identity/admin/test_roles.py
@@ -171,7 +171,7 @@
                                                        user['id'], role['id'])
         resp, body = self.client.remove_user_role(tenant['id'], user['id'],
                                                   user_role['id'])
-        self.assertEquals(resp['status'], '204')
+        self.assertEqual(resp['status'], '204')
 
     @attr(type='gate')
     def test_remove_user_role_by_unauthorized_user(self):