Missing nodejs compatibility; add engines data to package.json

[ccjoel]

I was setting up the project locally, and npm install failed with a lot of errors.

The problem was that I was using node v12.16.1 on my system.

Which version should I use in order for this step to be successful? Well... I checked the Dockerfile contents and saw that we pull a node:8 image. I switched my node version to 8 and voila- it worked.

package.json allows the inclusion of a field to describe compatibility for runtimes and versions. This can be guidance, or can be set to warn users, or possibly error. This issue is to add this field to describe which versions of node/npm are compatible with this project.

See engines.