request: option to make checkDependencies() advisory (not mandatory)?

[Ron Waldon-Howe]

Loving this project so far. It definitely streamlines those first few hectic moments in React land.

I prefer to split my package.json a certain way:

• dependencies: runtime requirements, which for a front-end only app does not include anything server-side
• devDependencies: testing, building, pretty much anything that isn't in dependencies

Anyhow, I've noticed that when I do this, react-project start refusing to run with a message:

You are missing some dependencies, please run:

Is it possible to have a --force CLI flag to proceed even when there are warning?

Or perhaps have the check be based on the presence of the packages on the file-system rather than what is in package.json?

Perhaps even apply SemVer rules when determining whether or not to consider a desired package and version to be missing?

Is any of this something that you'd welcome a PR for?