Now that all firewall ports are explicitly specified for all services,
it is safer to remove automatic infering of firewall service name from
systemd service name. This Closes: #468 where firewall status is
being shown for 'software upgrades'.
The Service object now offers handling services on a system level,
and gathering information whether it's enabled or running.
New methods: enable, disable, is_enabled, is_running;
For this it needs the correct (system-level) service name.
All of the methods can be overridden/customized.
This changes all modules to the new Service object and deletes
action scripts that are not required anymore.
