security/py-hkdf: import py-hkdf-0.0.3

Packaged for wip by Matthias Ferdinand.

This module implements the HMAC Key Derivation function, defined at

    http://tools.ietf.org/html/draft-krawczyk-hkdf-01

There are two interfaces: a functional interface, with separate extract
and expand functions as defined in the draft RFC, and a wrapper class
for these functions.

(wiz)