Sort all Python imports

[mbeacom]

The goal of this PR is to sort all Python imports for readability in the following order:

• Future
• Python Standard Library
• Third Party
• Current Python Project
• Explicitly Local (. before import, as in: from . import x)
• Custom Separate Sections (Defined by forced_separate list in configuration file)
• Custom Sections (Defined by sections list in configuration file)

You can automatically format your Python imports with the package isort.

[aldenpeterson-wf]

+1 though I hope you did this automatically somehow, hah!

[mbeacom]

@aldenpeterson-wf Of course! Hah.
I regularly use isort

[heyman]

Please note that gevent's monkey patching must be applied before the import of requests (see #655). Perhaps isort can be configured to not touch that if we run it again (or we can just manually fix it).