Drop openstack-common.conf
Drop openstack-common.conf

We no longer need openstack-common.conf
as oslo-incubator has been retried.

Change-Id: I8caf41cb257f16e8800d18d7dfa62def7683c3b5

openstack/networking-nec,stackforge/networking-nec,openstack/networking-nec,stackforge/networking-nec