Remove obsolete info from Fall 2013 bthon page.

Just to avoid giving out confusing info in case anyone stumbles across
this before we get the details.

The A^2 info is still there in the history if we want to revive it later
to use as a template.
Remove ldap info

Poeple don't usually seem to take us up on this offer.  It was fairly
easy to reserve this stuff on the fly using the setup we had in A^2,
let's plan on doing it that way again instead.