Dependency cleanup

[twm]

• Remove setup.cfg [metadata] section, which didn't match setup.py and is deprecated anyway.
• Instead of depending on Twisted's various TLS dependencies directly, depend on Twisted[tls] which has been present since at least Twisted 16.0.0 (but retain a higher PyOpenSSL dep for Python 3, since Twisted[tls] requires a lesser version).

[glyph]

Hopefully CI will be happy, but I'm inclined to merge.

[tomprince]

It looks like the virtualenv that travis defaults to has a setuptools that isn't new enough to correctly support the environment markers used.

[glyph]

It looks like the virtualenv that travis defaults to has a setuptools that isn't new enough to correctly support the environment markers used.

Wait... virtualenv is the component that reads these descriptions?

[markrwilliams]

virtualenv vendors setuptools & pip. That's where a new virtual environment's setuptools & pip come from.

Maybe put a `pip install -U virtualenv` in the Travis config?

[twm]

Is it not a serious problem that old setuptools can't install the package? I mean, the Python packaging morass wouldn't be such a problem if we could count on users to have the latest pip installed, would it?

Could we just require pyOpenSSL >= 0.15.1 in all cases? 0.13 is from 2011. The only reason I see keep using it (based on the changelog) is that it is the last release prior to cryptography and the associated cffi deps. Still, treq is unabashedly oriented towards communication on the Internet, and one should not communicate on the Internet with software from 2011...

[codecov-io]

Current coverage is 96.31% (diff: 100%)

Merging #155 into master will not change coverage

@@             master       #155   diff @@
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  Files            19         19          
  Lines          1710       1710          
  Methods           0          0          
  Messages          0          0          
  Branches        152        152          
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  Hits           1647       1647          
  Misses           42         42          
  Partials         21         21          

Powered by Codecov. Last update 768c3f6...6dad622

[tomprince]

Requiring a newer version seems reasonable (twisted 16.4 is requiring pyopenssl 16.0.0 anyway).

Regarding newer pip/setuptools, I know the most recent version of pip was the most common downloader on pypi a day after it was released.

[twm]

service_identity has also dropped support for pyOpenSSL < 0.14, so I think that bumping treq's dependency is definitely the right move. I'm working on shepherding Travis to success now, which is proving a little difficult with the Fastly TLS incident.

[twm]

@glyph If you still wish to merge, we're green here.