The package-upgrade action performs package upgrades for the current
OpenStack release.
The code path used is similar to the openstack-upgrade action, with the
difference being that package-upgrade will not execute if an openstack
upgrade is available (based on the openstack-origin setting).
This change includes a charm-helpers sync.
Change-Id: Ifd99ea307a6e4d1d034d7c1e494e2cd8abd894e9