please add a 'region_name' configuration in kuryr/lib/config

In kuryr/kuryr/lib/utils.py, the neutronclient function is as follows:

   def get_neutron_client(*args, **kwargs):
       conf_group = kuryr_config.neutron_group.name
       auth_plugin = get_auth_plugin(conf_group)
       session = get_keystone_session(conf_group, auth_plugin)
       endpoint_type = getattr(getattr(cfg.CONF, conf_group), 'endpoint_type')

       return client.Client(session=session,
                            auth=auth_plugin,
                            endpoint_type=endpoint_type)

However, in multi-region scenario (For example, Tricircle scenario), some users need to specify which region's neutronclient api to call, so that they can implement their own neutron network function.

So, I think you can add 'region_name' configuration in neutronclient function. Maybe like this:

    def get_neutron_client(*args, **kwargs):
        conf_group = kuryr_config.neutron_group.name
        auth_plugin = get_auth_plugin(conf_group)
        session = get_keystone_session(conf_group, auth_plugin)
        endpoint_type = getattr(getattr(cfg.CONF, conf_group), 'endpoint_type')

#++# region_name = getattr(getattr(cfg.CONF, conf_group), 'region_name')

#**# return client.Client(session=session,
                             auth=auth_plugin,
                             endpoint_type=endpoint_type,
                             region_name=region_name)

Meanwhile, register 'region_name' option in kuryr conf.