* Enhance Jest config error for `setupTestFrameworkScriptFile`

I wasn't aware of the fact that users of c-r-a could just define
`src/setupTests.js` and it would be configured with Jest - I nearly
ejected before I found a GitHub issue that confirmed this functionality.

I thought it might be a nice idea to add it to the error about Jest
config overrides to stop others ejecting when they don't need to.

* Change the order of Jest config errors.

* Show different error for `setupTestFrameworkScriptFile`

* Tweak the message

* Try to fix CI

* Bump Jest elsewhere

* Bump Babel elsewhere

* Fix CI on Windows by writing .cmd file back

* Support Jest --watchAll flag

* Use clearer condition

* Add comma

* Offer to set browser defaults

* Catch error on no

* Add ending newlines

* Ensure we re-check to prevent defaults from leaking

* Reduce nesting

* Add defaults message

* More explicit

* Warn about browsers during build

* Better message

Add preflight check to guard against wrong versions of webpack/eslint/jest higher up the tree (#3771)

* Run real scripts in local development

* Add preflight check warning

* I know what I am doing

* Move preflight check into individual scripts

This ensures we don't try to filter NODE_PATH twice, accidentally removing the now-absolute path.

* Slightly tweak the wording

* Fix lint

* Provide better defaults

* Let babel determine features to compile

* meh

* Remove setting of BABEL_ENV

* Revert "Remove setting of BABEL_ENV"

This reverts commit ee2db707.

* Set browsers to ie9

* update jest to 21.0.2 to support watchPathIgnorePatterns configuration

* update jest to 21.1.0

* Try bumping Jest

* Bump babel-jest

* Try to debug weird CI failure

* Remove debug code

* Bump other Jest packages

* ffs

* temp

* Revert "temp"

This reverts commit 62aec9ac.

* Add warning when HOST environment variable is set (#3719)

* Improve HOST environment variable warning message

* Adjust text and message

Closes #3719

the code got updated from `detect()` to `choosePort` while the comment did not.

* improve eject message

* cross os implementation

* File headers BSD+Patents -> MIT

* BSD+Patents -> MIT

* rerun prettier for all files

* pin prettier to 1.6.1

* Move the reduction of the messages to a single place in the place it is used.

* Fix variable name

* format UglifyJs error

* move formatBuildError to react-dev-utils

* fix readme

* use regex for plucking the path from stack

* make path human readable and fallback to show error if regex not matched

* rename to printBuildError and add link to the docs

* fix link indentation

* improve readibility + shorten link

Jest's default value for this option is ["js", "json", "jsx", "node"].
CRA's current value is ["web.js", "js", "json", "web.jsx", "jsx"], which
is missing one of default ones: "node". This change fixes that.

This "node" extension is used in packages that use native code.

* Better React Native Web support

* Adding better react-native-web support for jest testing

* Put react-scripts in dependencies, not devDependencies

* Sort dependencies on eject

* Remove CI check

* Fix incorrect check if CI variable is set to true

Originally build would fail on warnings with any value of CI environment variable. Now it will correctly check if it's true.

Discussed here: https://github.com/facebookincubator/create-react-app/issues/2453

* Check for "not false" instead of "not true"

After discussion we decided that this will be closer to current functionality and not break anything.

* Print file sizes with correct build folder path.

* Just use the print the basename.

* Remove unnecessary dependencies(#751)

* Sort alphabetically

* Ejecting should ensure you have clean git status

* Rename function

* Style

* Minor changes

- extract function
- exclude error output for missing git
- more descriptive error message
- no need to mutate answer
- fix answering "no" to return 0 exit code

* Show warnings for builds

* Move WebpackDevServer helpers into react-dev-utils