In order to facilitate periodic deployment and upgrade testing,
this patch implements an 'action' as a second CLI parameter for
the gate-check-commit script.
This seperates the 'action' from the 'scenario', allowing us to
execute a gate-check-commit for multiple scenarios instead of
being stuck with only one. That is why the 'upgrade' scenario
is removed.
This patch is partnered with this project-config change:
https://review.openstack.org/419517
The patch also tidies a few things up in order to make the
script a little more readable.
Change-Id: Ie62efc188d5eafd5bb64eb53f14c191dd50bef33