Make app PWA

[TMcMeans]

Implement Progressive Web App (PWA) technologies like: background sync, IndexedDB, static assets caching using a Service Worker

[ashtonkbailey]

• [x] Site is served over HTTPS
• [x] Pages are responsive on tablets & mobile devices
• [ ] All app URLs load while offline
  • to do this use a service worker (https://developers.google.com/web/fundamentals/primers/service-workers/)
• [ ] Metadata provided for Add to Home screen
  • add to manifest file (https://developers.google.com/web/fundamentals/web-app-manifest)
• [ ] First load fast even on 3G
  • many ways to fix (https://developers.google.com/web/fundamentals/performance/)
• [ ] Site works cross-browser (test with Lighthouse)
• [ ] Page transitions don't feel like they block on the network
  • our fix will be a loading gif, but can implement some nice transitions as well
• [x] Each page has a URL