Update flake8 config to work with black
Update flake8 config to work with black

As the first step to update the code to use the black code formater,
make the flake8 config play nice with black.

Add
https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#line-length

sontek/pymemcache,sontek/pymemcache,pinterest/pymemcache,pinterest/pymemcache