This is the best behavior so people have seamless upgrades to new React majors.

This is probably a terrible default warning from the ESLint plugin, and we need to wait for https://github.com/yannickcr/eslint-plugin-react/issues/1955 before changing this hardcoded behavior.

Closes #5034

Closes #5020

Closes #4932, Closes #4876

* No lock files prevents the use of yarn upgrade & outdated

* Update deps

* Bump Jest across the board

* Add safe postcss parser

* Updates to reflect service worker registration being opt-in.

* Fixed an anchor link.

* Updates to SWPrecacheWebpackPlugin config, and corresponding docs.

* Upgrade html webpack plugin

* Fix build

* Disable webpack chunk rollup

* Bump timeout

* Revert "Bump timeout"

This reverts commit 84632115d178b48e08eb75dc5e9a921ece6aa759.

* Revert Lerna dependency, there's too many bugs in v3

* Remove `mjs` support

This reverts commit b43ad04b.

This reverts commit aa8789b1.

This reverts commit 47d2d941.

This reverts commit 2c34d5b6.

This reverts commit 058d03f8.

Uglify is no longer maintained and has bugs not present in Terser (its successor)

The `formatter` option is incompatible with with `thread-loader`.
The `formatter` option previously accepted a function which was lost during JSON serialization.

* Update jest version

* Update babel-jest version

* Use testURL: http://localhost in jest configs.

* Update to jest version 23.5

This version of jest includes a fix for https://github.com/jsdom/jsdom/issues/2304

* "testURL": "http://localhost" is default with jest v23.5

This fixes the functionality of this dependency for Node 10 and above.

Refs: https://github.com/webpack/webpack-dev-server/pull/1451
Refs: https://github.com/nodejs/node/issues/21665

* support scoped packages for cra --scripts-version option

* enable safe option to cssnano processor

Fixes #4682

* support scoped packages for cra --scripts-version option

* seperate out kitchensink test

* add eject to node 6 testing

* travis node 6 eject

* fix CI warnings

* Suggest `reactstrap` instead of `react-bootstrap`

* Update README.md

To analyze Webpack bundles, a "stats" JSON is required.

This PR allows that file to be created and saved to the `build`
directory, so that users can use it with Webpack-specific insight
tools like `webpack-bundle-analyzer` without ejecting their
application.

Updated the README to include details for how to do this.

* Update paths.js, rename shadow path variable

This file requires the "path" module and sets it to a variable `path`. The function `ensureSlash` also has a variable `path` that then shadows the `path` module.

* Update paths.js

* Removes Chokidar Recursive Flag

According to the changelog it is not necessary anymore as it doesn't do anything.

* Removes initial build on SCSS watch

Chokidar now does this on it's own.

* Removes sass watch recursive, default include-path

as proposed by @michaelwayman

* Removes another left-over build-css

Support for .mjs files added in #3239 did not account for npm libraries which ship native mjs files alongside js files. This accounts for this by ensuring .js files resolve before their accompanying .mjs file. Note that this is not an ideal end state since selecting a .mjs over a .js extension should be the result of whether `import` was used instead of `require()` in a node environment with native ESM support (currently via `--experimental-modules`). Instead, this change just *always* selects a .js extension before the .mjs extension if it exists.

This unbreaks support for using GraphQL (relay, apollo, etc) within create-react-app projects.