Updated openstack/openstack
Project: openstack/ceilometer  0b9403540ac3e51dc652831fc0afb787418a711f

remove default=None for config options

In the cfg module default=None is set as the default value.

Change-Id: I65786401354e5fb966339cbdb4a76f5f628b8d6f
Closes-Bug: #1323975