Add flake8 config with all currently passing rules enabled.
Add flake8 config with all currently passing rules enabled.

Running flake8 prior to committing new Python code makes sure that no
regressions w.r.t. PEP 8 compliance are introduced.

Please note that all potentially controversial PEP 8 rules are disabled in this
config file. Only the remaining non-controversial and currently passing rules
are kept enabled.

Running flake8:
$ flake8

Installing flake8:
$ pip install flake8

khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift,khizkhiz/swift