Ssl version named constants

[javabrett]

I found that I had this old contribution lying around without a matching PR.

Fixes #1454 , fixes #1114 . /cc @tilgovi .

[sirkonst]

What about negative tests, with wrong setting?

[javabrett]

@sirkonst I added a commit which adds the negative tests, and tightens-up validation on the integer version of the constants (these were previously only checked for positive-integer, they now need to match a valid ssl.PROTOCOL_... value.

Removed Python 2.x tests and shuffled the remainder to match the ever-shifting sands of these constants across Python 3.x ssl.

[javabrett]

Also any +1's or -1's on #1680 appreciated.

[berkerpeksag]

Could you please squash all commits into one and add your name as the co-author of the patch in the commit message?

Co-Authored-By: Brett Randall <javabrett@gmail.com>

THANKS file needs to be updated as well.

[javabrett]

I've returned to this with a rebase/squash, updated THANKS and amended the commit message. I'll add some new commits for the feedback and squash those later.

[javabrett]

Feel free to squash those last few commits before/during merge, or re-review and I will squash them.

[benoitc]

ping @berkerpeksag ok to merge? what's missing?

[berkerpeksag]

@javabrett you can squash these commits after you address my latest review comments. I'd do it myself before merge, but there is a bug in GitHub when a PR is authored by multiple authors and the merger use the "squash" option, so we may not able to attribute your work correctly in the squashed commit. It's much safer if you squash the commits yourself and add the following line to the commit message:

Co-Authored-By: Brett Randall <javabrett@gmail.com>

Thanks!

[berkerpeksag]

@javabrett thank you for finishing this! I think this change will make Gunicorn much more user friendly.