template config

[tjstebbing]

Pup manifests are supposed to support using {{template}} variables in services, ie:

"exec": "/bin/run.sh --port={{.config.PORT}}"

We also had conceived of being able to template whole config files to be written with injected template variables for wrapped services that use config files.

The object presented to the template should be a composite of the config set by the user based on the manifest fields, as well as the environment vars, auto-assigned ports and other details that Dogeboxd generates.