Remove dependencies on pep8, pyflakes and flake8

They should be determined by the hacking dependency
implicitely.

Change-Id: I8e2c5700d685424db69150edf2ed9290eba83e7e
Update setup.cfg for the Neutron -> Quantum handler rename

Change-Id: I38104fa1ff9a9590198b9081e6fd683dcaa520fe
Closes-Bug: 1270111