Update cryptography to 2.1.1

[pyup-bot]

There's a new version of cryptography available. You are currently using 2.0.3. I have updated it to 2.1.1

These links might come in handy: PyPI | Changelog | Repo

Changelog

2.1

* **FINAL DEPRECATION** Python 2.6 support is deprecated, and will be removed
 in the next release of ``cryptography``.
* **BACKWARDS INCOMPATIBLE:** ``Whirlpool``, ``RIPEMD160``, and
 ``UnsupportedExtension`` have been removed in accordance with our
 :doc:`/api-stability` policy.
* **BACKWARDS INCOMPATIBLE:** :attr:`~cryptography.x509.DNSName.value`,
 :attr:`~cryptography.x509.RFC822Name.value`, and
 :attr:`~cryptography.x509.UniformResourceIdentifier.value` will now return
 an :term:`A-label` string when parsing a certificate containing an
 internationalized domain name (IDN) or if the caller passed a :term:`U-label`
 to the constructor. See below for additional deprecations related to this
 change.
* Installing ``cryptography`` now requires ``pip`` 6 or newer.
* Deprecated passing :term:`U-label` strings to the
 :class:`~cryptography.x509.DNSName`,
 :class:`~cryptography.x509.UniformResourceIdentifier`, and
 :class:`~cryptography.x509.RFC822Name` constructors. Instead, users should
 pass values as :term:`A-label` strings with ``idna`` encoding if necessary.
 This change will not affect anyone who is not processing internationalized
 domains.
* Added support for
 :class:`~cryptography.hazmat.primitives.ciphers.algorithms.ChaCha20`. In
 most cases users should choose
 :class:`~cryptography.hazmat.primitives.ciphers.aead.ChaCha20Poly1305`
 rather than using this unauthenticated form.
* Added :meth:`~cryptography.x509.CertificateRevocationList.is_signature_valid`
 to :class:`~cryptography.x509.CertificateRevocationList`.
* Support :class:`~cryptography.hazmat.primitives.hashes.BLAKE2b` and
 :class:`~cryptography.hazmat.primitives.hashes.BLAKE2s` with
 :class:`~cryptography.hazmat.primitives.hmac.HMAC`.
* Added support for
 :class:`~cryptography.hazmat.primitives.ciphers.modes.XTS` mode for
 AES.
* Added support for using labels with
 :class:`~cryptography.hazmat.primitives.asymmetric.padding.OAEP` when using
 OpenSSL 1.0.2 or greater.
* Improved compatibility with NSS when issuing certificates from an issuer
 that has a subject with non-``UTF8String`` string types.
* Add support for the :class:`~cryptography.x509.DeltaCRLIndicator` extension.
* Add support for the :class:`~cryptography.x509.TLSFeature`
 extension. This is commonly used for enabling ``OCSP Must-Staple`` in
 certificates.
* Add support for the :class:`~cryptography.x509.FreshestCRL` extension.

.. _v2-0-3:

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖

[pyup-bot]

Closing this in favor of #41