app.json (how to deploy apps that require specific resources/tasks e.g: elm-make before starting server)

[nelsonic]

see: https://devcenter.heroku.com/articles/app-json-schema
used in: https://github.com/healthlocker/healthlocker/blob/master/app.json
and: https://github.com/dwyl/hapi-socketio-redis-chat-example/blob/master/app.json

We need to write a brief intro to why an app.json file is useful for apps deployed to Heroku.

This work could be tied into helping people deploy the dwyl "chat/time" app to heroku. 🤔