Include Co-authored-by entries in AUTHORS

Import latest openstack.common.setup from oslo-incubator, which includes
the fix to include Co-authored-by entries in AUTHORS.

Fixes bug 1158319

Change-Id: I4f0ba09816730d10869c4ca639e2930d266eac8f
Merge "Include Co-authored-by entries in AUTHORS"
Merge remote-tracking branch 'm_src_repo/master' into build-temp