ignore build directory for pep8
ignore build directory for pep8

this mirrors the excludes from nova.

Change-Id: I0ca5f02918842fc708c704fcf2845936dc1c5965

hareeshpc/networking-cisco,nikolay-fedotov/networking-cisco,noironetworks/networking-cisco,noironetworks/networking-cisco,cisco-openstack/networking-cisco,Gitweijie/first_project,Gitweijie/first_project,Tehsmash/networking-cisco,CiscoSystems/networking-cisco,hareeshpc/networking-cisco,openstack/networking-cisco,openstack/networking-cisco,CiscoSystems/networking-cisco,Tehsmash/networking-cisco,cisco-openstack/networking-cisco