- Allow just a name entry, instead of requiring an object
entry; this makes "foo" equal to { name: "foo", runlevel: "default" }
and simplifies more for the straightfoward case of #974.
- Based on comments from #974, follow the configuration
scheme from services-systemd, so with separate lists
"services" and "disable". This ties it **slightly**
less closely to the commands passed to rc-config.
- If runlevel isn't set (at all) then use "default". For
most systems that do not use multiple runlevels, this
simplifies the configuration to just a list of service names
to add or delete.
- Document the functions some more
- Only "state" (i.e. action) "add" and "del" make sense,
avoid calling rc-update for other keys (e.g. typo's).
This matches the documentation, although there might be
other actions that make sense (see also services-systemd,
with its enable, disable and mask actions).
