build a container with spruce and jq

[bengerman13]

Right now we get certbot, jq, and spruce on the fly, which is slow and silly, but that doesn't matter much.
What does matter is that we get rate-limited sometimes trying to figure out which spruce to get.

We should build an image with spruce at least for this, and since we're already doing that, we might as well include jq and certbot