Make PWA installable and working offline

[tomaszlyszczyk]

It would be great if the app allowed for offline use.
I can add it to the home screen, but it's not working offline.

[dvmarinoff]

The issue here is that google made the whole installable app thing so complicated that pushing updates is just a painful experience that might get wrong at multiple levels.

I remember not long ago I read an article about them relaxing the conditions, but will need to look again in to it.
Will report again here later.