Attractor example is broken (again)

[jonathanrocher]

I believe I up to date on all of ETS and yet it seems like our attractor example is broken again:

jrocher$ python run.py 
WARNING:traits.adaptation.adapter:DEPRECATED: traits.adaptation.adapter.callback, use the 'register_factory' function from 'traits.api' instead
Traceback (most recent call last):
  File "run.py", line 27, in <module>
    main(sys.argv)
  File "run.py", line 20, in main
    app.run()
  File "/Users/jrocher/Projects/ETS_trunk/envisage/envisage/ui/tasks/tasks_application.py", line 134, in run
    self._create_windows()
  File "/Users/jrocher/Projects/ETS_trunk/envisage/envisage/ui/tasks/tasks_application.py", line 287, in _create_windows
    restore=self.always_use_default_layout)
  File "/Users/jrocher/Projects/ETS_trunk/envisage/envisage/ui/tasks/tasks_application.py", line 205, in create_window
    window.add_task(task)
  File "/Users/jrocher/Projects/ETS_trunk/pyface/pyface/tasks/task_window.py", line 180, in add_task
    state.central_pane = task.create_central_pane()
  File "/Users/jrocher/Projects/ETS_trunk/envisage/examples/plugins/tasks/attractors/visualize_2d_task.py", line 43, in create_central_pane
    pane = Plot2dPane(models=self.models)
  File "/Users/jrocher/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/traits/trait_types.py", line 2201, in validate
    return TraitListObject( self, object, name, value )
  File "/Users/jrocher/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/traits/trait_handlers.py", line 2309, in __init__
    raise excp
traits.trait_errors.TraitError: Each element of the 'models' trait of a Plot2dPane instance must be an IPlottable2d or None, but a value of <model.lorenz.Lorenz object at 0x124b81830> <class 'model.lorenz.Lorenz'> was specified.