Cleanup more pylint/pep8/apidoc errors

Hopefully this makes stable-2.15 clean and able to pass a buildbot run.
The changes should all be self-explanatory, except test/mocks.py one:
there were more unused arguments, so I added a silence for that at class
level, and removed the '_' on _ec_id since it was superfluous now.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Brian Foley <bpfoley@google.com>
5 files changed