Check offline mode for web app

[bashor]

It seems to me we need to add more URLs to staticUrlsToCache

[JSMonk]

@bashor Did you notice some that should be added?

[bashor]

It doesn't work in many places if I go offline after a first load without opening anything else. Please check all screens.

[bashor]

It might be due to other reason, IDK.

[bashor]

Also, I noticed that currently SW is not robust enough and could be broken with uncaught exceptions, e.g. due to connection issue or unsupported protocol (chrome-extension://).

[JSMonk]

I don't cache the API requests (network-then-cache), so if a participant tries to fetch the application for the first time without the internet - there will be no cache to load the application. Users should run the application at least once to use it offline.