ignore build directory for pep8
ignore build directory for pep8

this mirrors the excludes from nova.

Change-Id: I0ca5f02918842fc708c704fcf2845936dc1c5965

openstack/networking-plumgrid,fawadkhaliq/networking-plumgrid,msagheer/networking-plumgrid,stackforge/networking-plumgrid,stackforge/networking-plumgrid,msagheer/networking-plumgrid,fawadkhaliq/networking-plumgrid,openstack/networking-plumgrid