Import latest openstack.common.setup
Import latest openstack.common.setup

Import latest openstack.common.setup from oslo-incubator.
Fixes bug 1158319 (Include Co-authored-by entries in AUTHORS), but also:
* stop using --stat for ChangeLog
* failing to get version from git
* returncode for Popen is valid only after communicate call

Change-Id: Ib7a391560ec885b5478208cd441ce2c10e9d8cac

Triv90/Nova,yrobla/nova,yrobla/nova,Triv90/Nova,Triv90/Nova,yrobla/nova