allow devs to use css modules for styling react components

[vanderhoop]

As a developer who wants the ability to scope css declarations to a particular element,
I want to configure webpack to use CSS modules,
So that I can style my components without polluting the global CSS scope.

Acceptance Criteria:

• developers are able to import stylesheets into their React component files like so:
  • import styles from "./css_modules/category_column.css"
• developers are able to reference the styles defined in a css module within their React components like so:

return (
  <section className={styles["category-header"]}>
  </section>
)

• the classNames are converted to globally unique strings within the app:

Desired Output:

<!-- format: css_module_name__class-name-from-css-module___alphaNumericString -->
<section class="category_column__category-header___3WpoB">
</section>