Slightly less useless landing page.

I'm trying to figure out how to reduce mixin usage for the headers, as
it adds a lot of unnecessary duplication.
Shorten expression.
Clear member object and access token on logout.
Session.anonymous and controller binding.

Sessions are anonymous if (1) there is no logged-in member or (2) the
logged-in member has no name.

Members that wish to enter records that involve ownership (videos,
profiles, comments...many other records) SHOULD have a member name.
(They don't have to, but we'd like to encourage naming.)

This predicate will soon be used to display an appropriate site map.