* add react-testing-library documentation/examples

* make react-testing-library a heading

* fix typo

 - react-dev-utils@5.0.1
 - react-scripts@1.1.4

 - react-scripts@1.1.3

 - react-scripts@1.1.2

Add troubleshooting for an issue that has to do with either 2FA, or using Windows, or both, when trying to deploy an app via gh-pages

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.

 - create-react-app@1.5.2
 - react-scripts@1.1.1

This reverts commit bab2c295.

I meant to apply it to `next` instead.

Update User Guide's README.md to include `json` and `css`
files in the command to format the entire project for the first time
with prettier, that it's consistent with the `lint-staged` command.

See #3837

 - babel-preset-react-app@3.1.1
 - create-react-app@1.5.0
 - eslint-config-react-app@2.1.0
 - react-dev-utils@5.0.0
 - react-error-overlay@4.0.0
 - react-scripts@1.1.0

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

* Improve HOST environment variable warning message

* Adjust text and message

Closes #3719

* Always include destructuring transform

* Fix lint

* Bump detect-port-alt

* Bump again

* Switch to Yarn Workspaces

* Feedback

* Move flowconfig

* Use publish script

* Keep git status check

* Fix Flow without perf penalty

* Remove Flow from package.json "test"

* Try running it from script directly (?)

* Try magic incantations

* lol flow COME ON

* Try to skip Flow on AppVeyor

* -df

* -df

* -df

* Try to fix CI

* Revert unrelated changes

* Update CONTRIBUTING.md

* add link to deployment docs after build

* Update printHostingInstructions.js

* Use proxy for all request methods other than GET

* Add comment

* Replacing literal 'build' with `buildFolder` variable

* Cleaning up the printHostingInstructions a bit

* Fixing undefined variable

* Extend --scripts-version to include .tar.gz format

* Removal of debug console.log

* added getProxy

getProxy checks proxy settings from process.env.https_proxy or Yarn (NPM) config (.npmrc)

* changed yarn for npm to get https-proxy 

default value for https-proxy is null, not undefined like in yarn

awk splits lines based on spaces, which causes directory names with spaces to end up in other fields. Using a for loop allows us to print from the 9th field onwards instead of just the 9th field.

* fix #2223 - [feature] Implement dotenv-expand to accept variable expansion in dot env files

* add to README TOC

* fix readme

* Update README.md

* add envinfo package, —info flag

* update envinfo to use new duplicates option

Added some more documentation to install the babel-preset-react-app making it more clear on how to get started with this preset outside of create-react-app.