"Integration" Testing: Tracking Successes

Looking for projects with `.babelrc` on github. Then run the command and check tests!

- [x] https://github.com/koliseoapi/react-data-input/pull/2
- es2015 -> env
- package renames
- dep updates
- add `@babel/core`
- rewrite `babel-register` in npm scripts
- [x] https://github.com/gaearon/react-side-effect/pull/44
- modify `mocha.opts`
- [ ] https://github.com/jamiebuilds/react-loadable
- [ ] ~~question: should we handle babel plugins that aren't used? is it possible to even know that?~~ skip for now
- [ ] if a config has loose in it, then even if a plugin switched the default to "spec" then we should add the loose option automatically.
- [x] handle nested `.babelrc` https://github.com/babel/babel-upgrade/pull/14
- [x] if using jest, add `"babel-core": "^7.0.0-bridge-0"` https://github.com/babel/babel-upgrade/pull/15
- [x] add `@babel/node` package if using `babel-node`
- [ ] modify `webpack.config.js` or js file configs

cc @eventualbuddha planning on using babel-codemod for the js changes

Start by reviewing the `.babelrc` integration targets and the command and tests used to check them. Focus on the remaining `react-loadable` checklist, including `webpack.config.js` or JavaScript configuration files, and use the referenced pull requests for context. Done means the supported configuration cases are handled and their tests pass.

Written by the indexing model from the issue text.