Support Heroku app.json file

I'd like to put my env vars and other config inside a "app.json" file (or maybe "app.yaml"). The format that Heroku supports might be suitable.

I plan to write a script that, similar to "kubectl apply", will sync that app config with a deis project.

I've been thinking that maybe there would be an interest for having this inside the deis CLI proper.
Thoughts?