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

* Add get-source-map tests

* Fixtures shouldn't be formatted

* Add mapper tests

* Add stack-frame tests

* Add more util tests

* Add unmapper tests

* Add parser tests

* Switch to snapshots

* Snapshot more