Add visual indicator that one or more addresses are still syncing

[Klakurka]

After a new button is added, we want to make it clear to people that they're not seeing the latest data yet if it hasn't managed to get processed quickly.

[Klakurka]

We have some basic text in place but it's certainly not what we want as a final solution.

Ideas:

1. Add an actual animation / spinner everywhere loading takes place.
2. Differentiate between "hang on while we grab your stuff" and "we've checked and there's nothing to show".