SHA256/512 Password Hashing for Pharo 5

Hi all,

I've updated my SHA256/512 password hashing library from NativeBoost to the
Pharo 5 FFI, added an authentication database that uses in-image persistence
and a very simple user interface written in Spec.

GH: https://github.com/PierceNg/PasswordCrypt/
Blog post: http://www.samadhiweb.com/blog/2017.02.18.shacrypt.html 

Pierce