This is in preparation for writing something that extracts them
into documentation.
user configurations now call config.system.service.foo.build { ...params }
instead of config.system.service.foo
the parameter type definitions themselves now move into the
config stanza of the module referencing the service
new helper function liminix.callService
The only service moved so far is dnsmasq
would be good to move more of this into a module, but that
doesn't sit well with the (potential) ability to run more than one
dnsmasq service, as modules are singletons
