A FailureApp should know its failure message

In my humble opinion, a FailureApp should know why someone woke it up.

For instance, in this example in devise: https://github.com/plataformatec/devise/blob/v3.3.0/lib/devise/strategies/database_authenticatable.rb#L17, it seems to be that `:not_found_in_database` is a useful piece of information that the FailureApp should have access to.