In order to be able to take an action after all the packages of the
module have been installed/updated or all the services have been
started/restarted, we set a 'nova-package' and 'nova-service' tag
for each package and service of this module.
At the moment, there is a generic openstack tag that is not specific
enough if one wants to take action upon a single module change.
Use case :
If an action needs to be taken after all the packages have been
installed or updated : Package <| tag == 'nova-package' |> -> X
Change-Id: I6a28ed68ba3b0cbdd14cc224e2cf0c253786064a
2a2005d4e9