* Fix paths in CSS files when homepage is set to "./"

In the production build, ExtractTextPlugin is used to generate a separate CSS file instead of injecting style through JavaScript. This plugin does not work well by default with nested output structure. To fix it, we give it a relative publicPath pointing to the build folder.

* Add section in README to explain how to make builds deployable anywhere

* Apply review requested change

* Apply review changes 2

* Add `PUBLIC_URL` env variable for advanced use (#937)
* Add support for `PUBLIC_URL` env variable
* Remove unnecessary duplications
* Simplify served path choice logic
* Honor PUBLIC_URL in development
* Add e2e tests

Enables serving static assets from specified host.

* Make all vars accessiable in index.html

* Fix wrong env provieded to DefinePlugin

* Separate results from getClientEnvironment

* The `string` should be object instead of string

* Fix accessing wrong field

* Changed variables naming to `raw` and `stringified`

* Remove trailing commas

* Let Jest handle all file types

* Update regexes

* Fix exclusion regex to also exclude files without extension
* Be over-cautious with Windows paths because I'm not sure how Jest handles them

* There is no automatic babel-jest discovery now that we use transsform

* Add Subresource Integrity support

* Pin dependency

* Remove path module from webpack config on eject.

Fixes #1174

* Move path module inclusion right after the other imports

Re: #1174

Revert webpack prod config comments to not refer to dev server.

Loads all files not already handled by other loaders.
Also, switch image loading from file loader to url-loader.

Enable sourcemaps in development

* Update css-loader to 0.26.0

* Update the production webpack config

In the `create-react-app` command, try to install packages using Yarn.
If Yarn is not installed, use npm instead.

In `react-scripts`, detect if the project is using Yarn by checking if
a `yarn.lock` file exists. If the project is using Yarn, display all
the instructions with Yarn commands and use Yarn to install packages
in `init` and `eject` scripts.

Upgrade `babel-loader` and remove the cache directory configuration
that was added in #620. `babel-loader` now uses the
`./node_modules/.cache/babel-loader` directory by default, so the
custom config is no longer needed.

* Create asset filenames mapping on the build output

I use danethurber/webpack-manifest-plugin on Webpack production
configuration to create a file named `asset-manifest.json` which contain a
mapping of all asset filenames to their corresponding output file.

`asset-manifest.json` will be located at the root of output folder.

This'll resolve #600

* Add an explanation for ManifestPlugin

* Make webpack-manifest-plugin's version exact

* Define process.env as object

* Fix define process.env

* fix NODE_ENV check

* Fix style nitpick

* Typo fix in webpack.config.dev.js comments

* Typo fix in webpack.config.prod.js comments

* Add syntax error overlay in development

* Support HMR being disabled

* Tweak CSS

* Extract some utilities into a separate package

* Add utils dir to `files` in package.json

* Do not create an empty `utils` dir on eject

Fixes #410, #674

* Move ESLint configuration to a separate package

* Remove the ESLint configuration, moved to eslint-config-react-app

* Update ESLint instructions

* Pin the package versions in eslint-config-react-app

* Add a README for eslint-config-react-app

* Update README.md

* Update README.md

* Update README.md

* Update README.md

* Update package.json

* Update package.json

* Update production eslint-loader config

* Add the ESLint config to devDependencies of the repo