Update cryptography to 2.2

[pyup-bot]

This PR updates cryptography from 2.1.4 to 2.2.

Changelog

### 2.2 ``` ~~~~~~~~~~~~~~~~ * **BACKWARDS INCOMPATIBLE:** Support for Python 2.6 has been dropped. * Resolved a bug in ``HKDF`` that incorrectly constrained output size. * Added :class:`~cryptography.hazmat.primitives.asymmetric.ec.BrainpoolP256R1`, :class:`~cryptography.hazmat.primitives.asymmetric.ec.BrainpoolP384R1`, and :class:`~cryptography.hazmat.primitives.asymmetric.ec.BrainpoolP512R1` to support inter-operating with systems like German smart meters. * Added token rotation support to :doc:`Fernet </fernet>` with :meth:`~cryptography.fernet.MultiFernet.rotate`. * Fixed a memory leak in :func:`~cryptography.hazmat.primitives.asymmetric.ec.derive_private_key`. * Added support for AES key wrapping with padding via :func:`~cryptography.hazmat.primitives.keywrap.aes_key_wrap_with_padding` and :func:`~cryptography.hazmat.primitives.keywrap.aes_key_unwrap_with_padding` . * Allow loading DSA keys with 224 bit ``q``. .. _v2-1-4: ```

Links

- PyPI: https://pypi.python.org/pypi/cryptography - Changelog: https://pyup.io/changelogs/cryptography/ - Repo: https://github.com/pyca/cryptography

[codecov-io]

Codecov Report

Merging #27 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #27   +/-   ##
=======================================
  Coverage   95.54%   95.54%           
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  Files           4        4           
  Lines         628      628           
  Branches      151      151           
=======================================
  Hits          600      600           
  Misses         12       12           
  Partials       16       16

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