Remove dependencies on pep8, pyflakes and flake8

They should be determined by the hacking dependency
implicitely.

Change-Id: Ie659b9f7b31391805ab5627464a0dfece40104ad
There are no mox tests, so remove dependency

Change-Id: Ic060988e0dbe3891a0ed05439c7db8cad65ad6bc
Merge "Remove dependencies on pep8, pyflakes and flake8"
Merge "There are no mox tests, so remove dependency"