Fixed tox -egenconfig Error
Fixed tox -egenconfig Error

tox -egenconfig Error:
AttributeError: 'module' object has no attribute 'base'
Caused by the ceilometer/agent/base.py removed

Closes-Bug: #1496684

Change-Id: I3d7f569397532b3e6f550e88b7a779567e83fca3

idegtiarov/ceilometer,maestro-hybrid-cloud/ceilometer,openstack/ceilometer,redhat-openstack/ceilometer,ityaptin/ceilometer,eayunstack/ceilometer,maestro-hybrid-cloud/ceilometer,fabian4/ceilometer,cernops/ceilometer,isyippee/ceilometer,cernops/ceilometer,ityaptin/ceilometer,openstack/ceilometer,isyippee/ceilometer,redhat-openstack/ceilometer,eayunstack/ceilometer,fabian4/ceilometer,idegtiarov/ceilometer