Add placeholder when no checklists are present

... add the same language from the tour.
Admin: Show contact email address if possible

Show the contact email address instead of
the sign-in address for the member list on
the admin page.
Make fewer initial tasks on circle creation

Let's make the initial task list just have
three things: a welcome, a note about the
tour, and the black task.

Also for non-new accounts, just add the
black task.