WIP: Percolate flags from the service to the units.

I think it'd be valuable to have the tests here a little more thorough by having multiple services and making sure that the events are triggered only for the models that have the event triggered so that you can be sure binding is done correctly and only hits the expected places. So I'd have three models, for instance, and set one to highlight, one to hide, and one to fade, and make sure each was as expected. Then I'd do the reverse to make sure it would unset correctly as well.