Cache some words/images on the frontend

[dpikt]

This would allow for offline usage of the app, as well as prevent the loading flash for the image.
If you wanted to get crazy, this might be a good use case for a service worker.

[rkillackey]

Nice, thanks! Yeah, caching was our initial thought as well (or using chrome storage). We just didn't quite have time to figure out how to handle previously viewed translations...We're working on a solution at the moment, but I will definitely look into using service workers!