Make ENC curl script more flexible.

Why would you want to edit the script every time you need different
data?

This change lets you just pass the `nodename` as an argument.
Actually, we're both wrong. It should be `node_name`. https://docs.puppetlabs.com/references/latest/configuration.html#nodename

That  being said, I'm being pedantic about how puppet identifies nodes, so yeah, just a sec.