user_domain_name is not passed to cinderclient

[Celia Wang]

>>> from cinderclient import client
>>> cinderv3 = client.Client('3', 'ehuan001', 'Ediw662a!', 'nspOS-devops', 'http://135.228.144.61:5000/v3', user_domain_name='Users', cacert='')
user_domain_name: Default

We call cinderclient and pass user_domain_name='Users', but actually the value of user_domain_name is not passed to cinderclient, it still use "Default".

Becuase in this code, when v3 cinderclient pass user_domain_name parameters to cinderclient in kwargs, but _construct_http_client doesn't get user_domain name.
https://github.com/openstack/python-cinderclient/blob/master/cinderclient/client.py

def _construct_http_client(
.....
 else:
        # FIXME(jamielennox): username and password are now optional. Need
        # to test that they were provided in this mode.
        logger = kwargs.get('logger')
        return HTTPClient(username,
                          password,
                          projectid=project_id,
                          auth_url=auth_url,
                          insecure=insecure,
                          timeout=timeout,
                          tenant_id=tenant_id,
                          proxy_token=proxy_token,
                          proxy_tenant_id=proxy_tenant_id,
                          region_name=region_name,
                          endpoint_type=endpoint_type,
                          service_type=service_type,
                          service_name=service_name,
                          volume_service_name=volume_service_name,
                          bypass_url=bypass_url,
                          retries=retries,
                          http_log_debug=http_log_debug,
                          cacert=cacert,
                          auth_system=auth_system,
                          auth_plugin=auth_plugin,
                          logger=logger,
                          api_version=api_version
                          )