New redirect strategy

I change the way the redirect strategy works.
The redirects from authenticate/logout actions are now callbacks.
This way the user can overwrite the default callback and decide **exactly** what to should happen.

ping @Ocramius

closes #479
closes #476
closes #473
closes #469
This is mostly because of BC. It is possible with current versions, and i want to backport this into 1.x and 0.x branches.