PyCA cryptography 2.2.1 released

[Paul Kehrer]

PyCA cryptography 2.2.1 has been released to PyPI. cryptography includes
both high level recipes and low level interfaces to common cryptographic
algorithms such as symmetric ciphers, message digests, and key derivation
functions. We support Python 2.7, Python 3.4+, and PyPy.

Changelog (https://cryptography.io/en/latest/changelog/#v2-2-1
<https://cryptography.io/en/latest/changelog/#v2-2>):

* Reverted a change to GeneralNames which prohibited having zero elements,
due to breakages.
* Fixed a bug in aes_key_unwrap_with_padding() that caused it to raise
InvalidUnwrap when key length modulo 8 was zero.

-Paul Kehrer (reaperhulk)