Provide file extension when when looking for files
Provide file extension when when looking for files

* Allow an extension to be passed to find_config files, defaulting to '.conf'

Change-Id: I022a3b28d9067158e9ed0da741a5e72cb73af167

citrix-openstack-build/pbr,emonty/oslo-packaging,WiFast/pbr,openstack-dev/pbr,JioCloud/pbr,varunarya10/pbr,varunarya10/pbr,JioCloud/pbr,openstack-dev/pbr,klmitch/pbr,redhat-openstack/pbr,citrix-openstack-build/pbr,citrix-openstack-build/pbr,redhat-openstack/pbr,WiFast/pbr,klmitch/pbr,openstack-dev/pbr,emonty/oslo-packaging