Manually mock service_catalog in stub_keystoneclient

MockObject.__init__ ignores properties, fixes:

FAIL: test_get_default_role (openstack_dashboard.test.api_tests.keystone_tests.RoleAPITests)
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Traceback (most recent call last):
  File "/var/lib/openstack-dashboard-test/openstack_dashboard/test/api_tests/keystone_tests.py", line 78, in test_get_default_role
    keystoneclient = self.stub_keystoneclient()
  File "/var/lib/openstack-dashboard-test/openstack_dashboard/test/helpers.py", line 287, in stub_keystoneclient
    self.keystoneclient = self.mox.CreateMock(keystone_client.Client)
  File "/usr/lib64/python2.6/site-packages/mox.py", line 258, in CreateMock
    new_mock = MockObject(class_to_mock, attrs=attrs)
  File "/usr/lib64/python2.6/site-packages/mox.py", line 556, in __init__
    attr = getattr(class_to_mock, method)
  File "/usr/lib64/python2.6/site-packages/mox.py", line 608, in __getattr__
    raise UnknownMethodCallError(name)
UnknownMethodCallError: Method called is not a member of the object: service_catalog
>>  raise UnknownMethodCallError('service_catalog')

Change-Id: I0af2f571855ad63c204e26d8283a713be0caae8f
Merge "Manually mock service_catalog in stub_keystoneclient"