Modernize logic for protecting against cached passwords from forms,
when users log out and other users use the back button (for Nora).
- switch to more modern caching prevention
- add CSRF protection to login form against forgery requests
- none of the cache-preventing mechanisms helps when the user
stores the password in the browser (no change to the past).
- For admins of existing sites: alter kernel parameter
"LoginPageExpirationTime" to 0 make use of this feature