Commit: f0dbcc7a692bc375e3e52a9661af4037392ee52f
Useful for cases such as warden, where a block configuration is taken.

    class SomeController < ApplicationController
      use RailsWarden::Manager do |manager|
        manager.default_strategies :facebook_oauth
        manager.failure_app = SomeController.action(:authorize)
      end
    end