Log Message:
Updated py-service_identity to 17.0.0.

17.0.0 (2017-05-23)
-------------------

Deprecations:
^^^^^^^^^^^^^

- Since Chrome 58 and Firefox 48 both don't accept certificates that contain \ 
only a Common Name, its usage is hereby deprecated in ``service_identity`` too.
  We have been raising a warning since 16.0.0 and the support will be removed in \ 
mid-2018 for good.

Changes:
^^^^^^^^

- When ``service_identity.SubjectAltNameWarning`` is raised, the Common Name of \ 
the certificate is now included in the warning message.
  `#17 <https://github.com/pyca/service_identity/pull/17>`_
- Added ``cryptography.x509`` backend for verifying certificates.
  `#18 <https://github.com/pyca/service_identity/pull/18>`_
- Wildcards (``*``) are now only allowed if they are the leftmost label in a \ 
certificate.
  This is common practice by all major browsers.
  `#19 <https://github.com/pyca/service_identity/pull/19>`_