Make tox config work.
Make tox config work.

Change-Id: Ic81c7bb0fa2fe5c73200a9195630a0d5bb999e7d

stackforge/networking-bigswitch,wolverineav/networking-bigswitch,wolverineav/networking-bigswitch,openstack/networking-bigswitch,stackforge/networking-bigswitch,openstack/networking-bigswitch