Update hacking for Python3

The repo is Python 3 now, so update hacking to version 3.0 which
supports Python 3.

Update hacking extension for newer flake8. Remove vi header check, this
is enabled as H106 already.

Fix problems found.

Change-Id: Ie4ccf0a1075995f5624a838388b6b0b46343129a
6 files changed