We're calling `add_breadcrumb` on the `Spotlight::Exhibit` object itself a few places.  If I'm not mistaken that links to the `#show` action of the relevant controller, which in the case of exhibits (`Spotlight::ExhibitsController`) does not exist.  This means, AFAICT, the exhibit title is a broken link in every breadcrumb.

I'm not sure if we should add a `Spotlight::ExhibitsController#show` action which renders the exhibit home page (might be nicer for polymorphic routes) or we should be linking directly to the home page from the breadcrumb.