Reformat code with "black"

[jedie]

I use "black" for all my codes... Think it would be good to reformat the code here, too.

[maerteijn]

I was thinking about at least a flake8 linter with import order. "black" is nice but not something the whole community agrees on (as pyflakes and pycodestyle).

[jedie]

I think "black" is very good. Just because you can't control anything except the line length.
So there are no "variants" of the format.

[maerteijn]

I did some basic formatting and applied it already, see the configuration here: https://github.com/django-oscar/django-oscar-docdata/blob/master/setup.cfg#L4

Works still needs to be done so I leave this issue open, to be continued.