All heat_tempest_plugin test failed with "No auth_url configured"

Issue

• All heat_tempest_plugin test failed with "No auth_url configured".

  Captured traceback:
  ~~~~~~~~~~~~~~~~~~~
      Traceback (most recent call last):
        File "/usr/lib/python2.7/site-packages/heat_tempest_plugin/tests/functional/functional_base.py", line 21, in setUp
          super(FunctionalTestsBase, self).setUp()
        File "/usr/lib/python2.7/site-packages/heat_tempest_plugin/common/test.py", line 139, in setUp
          'No auth_url configured')
        File "/usr/lib/python2.7/site-packages/testtools/testcase.py", line 374, in assertIsNotNone
          self.assertThat(observed, matcher, message)
        File "/usr/lib/python2.7/site-packages/testtools/testcase.py", line 435, in assertThat
          raise mismatch_error
      testtools.matchers._impl.MismatchError: None matches Is(None): No auth_url configured