* move SaltGeneration into HashPasswort and rename it to what it does
* Migration: Where Password is Valid with Empty String delete it
* prohibit empty password hash
* let SetPassword("") unset pwd stuff
* move SaltGeneration into HashPasswort and rename it to what it does
* Migration: Where Password is Valid with Empty String delete it
* prohibit empty password hash
* let SetPassword("") unset pwd stuff