* Support node scripts in BROWSER

Modify OpenBrowser.js to run node scripts specified with the BROWSER environment
variable . If the value of the BROWSER environment variable ends with '.js' a
child process is spawned to execute the script with node.js. Any
arguments passed to npm start are also passed to this script, as well as
the url where the app is served.
The command executed in the child process is:

node <pathToScript> [OPTIONS] <url>

Update User Guide.

* Tweak code style

* Pin dep

* Comment out 0.10 docs

* Support hoisting react-scripts

* require.resolve() loaders and configs

This makes it so that loaders and configs are resolved relative to the config rather than to the app. This seems to make more sense to me.

Removing a stylistic lint rule

* ESLint Config: Upgrade eslint-plugin-jsx-a11y and activate more rules.

* Try to fix Lerna

* Update README.md

* Remove html-has-lang

* Update README.md

* Unpin Yarn

* Try 0.24.2

* Update e2e-simple.sh

Matches what we did in https://github.com/facebook/react/pull/9679

* Upgrade to Jest 19

* Use testMatch

* Correct version

* Show network address on start

* Tweak visual representation

* Change proxy handling to allow multiple proxies to be specified in package.json.

* Up webpack-dev-server to 2.4.2

Webpack Dev Server version 2.4.2 handles the external websocket upgrade
for all proxies

* Fix the listen() call

* Switch to correct default host

* Remove promises and extract to react-dev-utils

* oops

* Warn for missing braces

* Overlay, too

* Tweak error and warning output

* Add a colon

* Add custom eslint formatter

* Add formatter docs

* Update formatter docs

* Slightly tweak it

* Update README.md

* Temporarily fork detect-port

* Fix get process id

* Use different package

* Unnecessary var

* Blacklist confusing global variables

* Blacklist globals

* Fix kitchensink test to lint

* Edit the list

* Use no-restricted globals for this

Closes #2127

* Don't collapse unintentional top-level errors

* Linkify internal stack frames too

* Click to view source

* Update package.json

* Update package.json

* Fix lint

* Browser sort is not stable

* Fix ordering of final message

* Register the warning capture

* Display only createElement warnings

* Use different method name

* Fix regression

* Ignore errors with only node_module files

* Ignore null files, too

* Revise count

* Revise warning

* Update overlay.js

* Add support for https://github.com/facebook/react/pull/9679

* Use absolute paths

* Trim path if it's absolute

* Make sure it's an absolute path

* Oops

* Tweak for new behavior

* Make it safer

* More resilient warnings

* Prettier output

* Fix flow

* Add note about yarn.lock in CONTRIBUTING.md

* Update CONTRIBUTING.md

* support different env configs.

* fomrat code

* Hide doc

* Slightly rework the PR

* Remove .env in default template
* Use just one entry in the paths
* Unify env.js and loadEnv.js

* Oops, forgot these folks

* update readme with fix from https://github.com/facebookincubator/create-react-app/issues/1939

* update with better globbing

* added note

* updating with a note and reverting previous changes

* how about this?

* refactor

* added note about new files back in after verifying locally

* spaces back in, sorry was my editor!

* removed note about new files :)

* added bullet about new files issue currently open on node-sass

https://github.com/facebookincubator/create-react-app/pull/2123#discussion_r116062043