Implement bash-hash

[makavity]

Possible to merge only after bash-f release
RustCrypto/sponges#92

[newpavlov]

bash-f v0.1.0 is released.

[makavity]

Thank you :)

[makavity]

@newpavlov i have one question, about bash-hash-prg.
In which repo it should be? This one? Same crate, or another?
Thank you.

[newpavlov]

I am not sure... Do you know how it's intended to be used? On the first glance it looks like a customizable XOF with somewhat weird restrictions on customization string (multiple of 4 bytes, no longer than 120 bytes).

It's probably should be part of this repository, but I am not sure whether we should put in bash-hash or into a separate crate.

[newpavlov]

Let's start with a separate bash-prg-hash crate.