Logout after password change

[neufeind]

In some environements it's considered a best practice to logout a user after changing the password and redirecting to the login-page again. If we don't want to implement the logout-logic ourselves, maybe there could be an option to redirect to a configurable URL after password-change for this purpose (so you can just redirect to a logout-url).

Meanwhile this can for example be implemented with the FinalUpdateEvent (also see #445).

[sbusemann]

good idea!