Update code to the Black code style

Summary:
Black code style "aims for consistency, generality, readability
and reducing git diffs". It's also PEP 8 compliant.

Ref T2058

Test Plan:

• woof CONTRIBUTORS.md
• woof -U
• woof -h

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T2058

Differential Revision: https://devcentral.nasqueron.org/D3535