AlertManager is a stateful service, and as such needs a writable
location for its data. Using the `StateDirectory` service unit
directive, we can configure systemd to create this directory
automatically, if it does not already exist when the service starts.
In order for the service to be able to write to the state directory, it
must have a stable UID. This means it cannot use the `DynamicUser`
service unit directive.
The *vmutils* package can be built from source easily, as its just a
collection of Go applications. Grafana and Alertmanager are quite a bit
more complicated because of their respective browser applications. In
the interest of getting this project actually going, we'll just install
the official binary releases of these (for now?).
