Revise Panes available by Role

[jeff-zucker]

The icons/panes a user can see have several problems. Foremost is that users do not have an under-the-hood pane unless they are a developer (in other words, they can't delete anything). Another issue is that since the spec doesn't mandate a preferences file, we should provide a default logged-in state. I don't understand why we present a sharing icon to the non-logged-in user. There are other inconsistencies. Here is my proposal. I would also be okay with simply logged in and logged out with logged in being all panes available.