Probably mostly useful for extended maintenance, but this adds a script
that can add a $series-em tag to all deliverables of a series as we
claimed we would do in the extended maintenance policy changes [0].
[0] https://docs.openstack.org/project-team-guide/stable-branches.html#extended-maintenance
Change-Id: Ibeec88bf4e81b97c523f416669e07a10aa86a53b
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>