Make moon configuration optional. Before the `attrNames` evaluated the
attributes eagerly, which in practice meant that you had to set a moon,
if there was a controller configured, which is not on purpose.
Add eval tests to the zerotier clanService module.
The vm module is a stub that acts as an api for the `generate-test-vars`
script, as that currently only works with a vm, not with an eval test.
This checks, if all the peers pick up their respective configuration
correctly. Without running the service itself.
