Make pep8 *the* linting interface
Make pep8 *the* linting interface

According to the PTI (=Python Test Interface,
http://governance.openstack.org/reference/cti/python_cti.html), pep8
is the interface for codestyle checks. Move all tests from linters to
pep8.

This basically reverts Ic9efdcb13978d2f29312a4a1f0fdd859d55c8398.

Depends-On: I9346e4bf8c3a50de088c6a157f0d871c0a9333a1
Change-Id: I99df6de57d345c40e39801d66575d35d0d8a36a9

himanshu-setia/keystone,mahak/keystone,rajalokan/keystone,dims/keystone,ilay09/keystone,klmitch/keystone,cernops/keystone,rajalokan/keystone,ilay09/keystone,openstack/keystone,openstack/keystone,mahak/keystone,klmitch/keystone,openstack/keystone,dims/keystone,cernops/keystone,himanshu-setia/keystone,mahak/keystone,rajalokan/keystone,ilay09/keystone