update webpack css include path, allow files to be loaded from the project root node_modules folder. (#178)

This project is a really good use case to apply some accessibility
rules to the lint config. For beginners getting started with React, we
can also teach/enforce basic accessibility rules in the web at author
time.

For now, I’ve just applied to the rules that are listed in
`eslint-config-airbnb` because these are most real-world tested, and we
can continue to add.

Happy to help if there are any questions/issues/concerns about the
plugin!

* Provide instructions on GH Pages deploy

* Add docs for GH Pages deployment

* Prevent incorrect paths in file-loader

* Minor message tweaks

* Update README.md

* Fix relative paths

* Don't assume the project is hosted at the root
* Require package.json in webpack.config.prod.js and use homepage if set; otherwise use '/'

* Fix package.json path and add sample package.json for tests

* Update publicPath to use relative path portion of URL defined in homepage

* Update successful bundle generation message

* Show bundle generation success message based on presence of homepage in package.json

Ref #156

Not sure if we can simply delete the line and that'll disable it, so I
went with setting it to 0. Let me know!

* Resolve imported CSS files from anywhere
* Resolve imported CSS files from src and node_modules folder only

Closes #103

See #72 for details

Local npm start and npm run build got broken by #33

* Make errors and warnings nicer

* Fix license stripping to not be eager

* Minor tweaks

Inspired by react-boilerplate setup

Fixes #31

This ensures errors are not tolerated.
Otherwise, Webpack just builds an empty bundle.

* Use a custom eslint rule list

* Sort rules

* Relax some rules