Add support for renaming with Jedi

[fsouza]

Leverages jedi's support for refactoring to implement rename.

This requires upgrading jedi. I can split this PR in two if preferred (first upgrade jedi, then add rename). Nevermind I see that #781 exists, once that's merged I can rebase.

Note: Jedi refactoring requires Python 3.6+, so I added 3.6 to CI. I didn't remove Python 3.5, but I believe at this point it's probably safe to do so. Thoughts? Also let me know if you'd rather go all the way to Python 3.8.

Closes #530.

[palantirtech]

Thanks for your interest in palantir/python-language-server, @fsouza! Before we can accept your pull request, you need to sign our contributor license agreement - just visit https://cla.palantir.com/ and follow the instructions. Once you sign, I'll automatically update this pull request.

[fsouza]

Oh I see that the upgrade to jedi 0.17.0 is being handled in #781. I can rebase my changes once that's merged.

[ccordoba12]

I didn't remove Python 3.5, but I believe at this point it's probably safe to do so.

I think so too. Please use 3.6 instead of 3.5 in our CIs.

[ccordoba12]

Thanks for this @fsouza! I left some small comments for you (please try to address them asap, so we can include your work in our next version).

[fsouza]

Hi @ccordoba12, thanks for the feedback. I'll be able to address it later today or tomorrow morning (EDT). No need to hold the release if that doesn't work for you.

Thank you! :D

[ccordoba12]

I'll be able to address it later today or tomorrow morning (EDT). No need to hold the release if that doesn't work for you.

If you can do it between today and tomorrow is fine. We still have to review and merge PR #754, which we plan to do tomorrow.

[fsouza]

@ccordoba12 I think I got it all. Thanks for all the feedback!

[ccordoba12]

Thanks @fsouza for addressing our review so quickly! I just left a minor suggestion, otherwise looks good.

[ccordoba12]

Don't worry about the failures in our tests. They are due to a new flake8 version.

[ccordoba12]

Thanks @fsouza!