Add password4j implementation of PasswordEncoder

[rwinch]

We should add a (or multiple?) password4j implementation of PasswordEncoder. I haven't looked at the API, so we might be able to get away with a single implementation (e.g. Password4jPasswordEncoder) that supports multiple algorithms. If not, then we may need multiple implementations (e.g. Password4jBCryptPasswordEncoder, Password4jSCryptPasswordEncoder, etc).

[mehrdadbozorgmehr]

Can I work on these issues? @jzheaux @rwinch

[rwinch]

Thanks for volunteering @mehrdadbozorgmehr Yes please send a PR 😄