Add a service worker using Workbox

[Zacharycampanelli]

As a developer, I want to identify use cases of service workers in a PWA.

As a developer, I want to add caching of all assets with Workbox's Generatesw class.

As a developer, I want to implement runtime caching.

As a developer, I want to use Workbox's InjectManifest class to generate a list of URLs to precache and use a custom service worker.