Define `Settings::BaseController#set_body_classes` so that sub classes
inherit `Settings::BaseController` don't need to define
`#set_body_classes` agein.

The specs for Settings::DeletesController include an example that
sets Settings.open_deletion to false and expects the "if deletion is not
available, redirect to root" logic to run.  However, this spec does not
set up a user, which means that the spec (intentionally or otherwise)
expects this redirection to work with unauthenticated access.

We should preserve that behavior.  To do so, we prepend the deletion
check to the action chain set up by Settings::BaseController, so that
said check occurs before the authenticate_user! check.

account before removing content for quicker feedback to end-users

* Add form for account deletion

* If avatar or header are gone from source, remove them

* Add option to have SuspendAccountService remove user record, add tests

* Exclude suspended accounts from search