* Installs and adds sass loader task in webpack for dev environment.

* Uses Timer's branch of sass-loader without node-sass dependency.

* Adds method for handling SASS modules.

* Fixes extension of excluded files when looking for scss modules.

* Adds support for both .scss and .sass extensions.

* Uses ExtractTextPlugin with sass-loader to bundle styles for the production build.

* Bundles SASS modules for the production build.

* Uses the latest version of sass-loader.

* Adds function to create different rules for style loaders in dev environment.

* Abstracts style loaders to a common function to avoid repetition.

* Simplifies the common function that creates style loaders.

* Creates assets for testing SASS/SCSS support.

* Creates mock components and unit tests for SASS and SCSS with and without modules.

* Creates integration tests for SASS/SCSS support.

* Adds node-sass as a template dependency so sass-loader can be tested.

* Includes sass tests when test component is mounted.

* Fixes asserted module name for sass and scss modules tests.

* Removes tests against css imports in SCSS and SASS files.

* Updates sass-loader to v7.

* Uses getCSSModuleLocalIdent from react-dev-utils.

* Fixes tests to match the use of getCSSModuleLocalIdent.

* Improves readability of getStyleLoader function.

* Uses postcss after sass.

* Refactors dev config to simplify common function for style loaders.

* Refactors prod config to simplify common function for style loaders.

* Use importLoaders config according to css-loader docs.