Add (already passing) sign_in_token option scenarii

Add FactoryGirl support to dummy app (was uncomplete)

Note: The addition to ActsAsTokenAuthenticationHandlerMethods is
questionnable.

I believe there should be a more elegant way to ensure that
the required Devise methods are available in test environment,
moreover I'm not really sure why they weren't already available :/.

I hope the way I included Devise::Controllers::SignInOut will make
this issue more visible :)