Support for staging builds

Hi, I thought about adding support for staging builds. I am not sure if this requires ejecting though, or could be a feature of CRA.

Our use case is that we create staging builds to deploy to our staging servers. This allows us to debug the app in a production like environment, but with the benefit of non-minimised code including proper sourcemap support and still includes the development warnings and notifications, as well as devtools support.

It can look very similar to webpack.config.prod.js, but with changes to L52-L54 and removal of webpack.optimize.UglifyJsPlugin.

[kfuchs]

This really should have been as simple as:

$ NODE_ENV=development npm build && s3 sync ./build/ s3://mybucket

You can’t really mistakenly use the dev keys when you’ve explicitly set it on NODE_ENV. By forcing the env keys it’s making it worse for everyone, because we can’t easily support multiple environments.

You shouldn’t try to save people from mistakes in there deployment process. A framework should provide the tools to support development, and a good one will help avoid pitfalls through documentation but not through pad locks 😃.

[msmfsd]

Bump - a staging build script would be good, or possibly the ability to override the NODE_ENV?