Changes related to SSL context

[notEvil]

Fixes #486 (introduced with python 3.10)

• SocketStream.ssl_connect now handles all arguments correctly (ca_certs and ciphers were incorrectly passed to context.wrap_socket)
• SSLAuthenticator now also uses SSLContext which enables hostname check (see https://docs.python.org/3/library/ssl.html#ssl.SSLContext.check_hostname)
• Both now rely on ssl.create_default_context to set reasonable defaults for ssl_version and cert_reqs. Former defaults led to inconsistencies (issue 486 is due to deprecation of PROTOCOL_TLS in python 3.10; check_hostname is enabled by default in python 3.10 conflicting with former default CERT_NONE)

I ran the ssl unittest with python 3.6 to check backwards compat

edit:
I left the docstrings untouched because I expect opinions regarding the switch to create_default_context. When the changes are accepted I don't mind updating the PR with changes to docstrings and the doc

[comrumino]

At a glance, things look good. I would be cool w/ you updating the docstrings. I will most likely merge after that. Thanks!

[notEvil]

In case you missed the commit, its there. Feel free to adjust

[comrumino]

I did miss the commit. Thanks for posting a comment! I'm working on getting more active in open-source again. Thanks for being a gem!