Don't expose pretty launch page to authenticated users

(I suspect you wanted this to view things as an admin, but if that's the case we should add it to an admin-only route!)
That page shows this page when signed in: ![screenshot 2014-12-15 23 42 51](https://cloud.githubusercontent.com/assets/90871/5448717/205f246a-84b4-11e4-923f-d203ef881207.png) so it should at least be an "anonymous-only" page. But it seems to have most of the info the launch page should have, so it might be redundant at this point.

I think it was mostly used for testing so you could see the sign up and log in links easily, but maybe it should also be admin-only?