implement cleaner user switching
Once we have design #704 for this, we need to actually build out the code that lets users cleanly switch identities and show which one they're in. Sometimes currently the app crashes, and it definitely gets restarted. The restart might be ok, but we need to know what's happening. Ideally it'd be as smooth as the way instagram and twitter do it.
go-ssb often crashes or hangs on the function ssbBotStop which we call when switching identities. Presumably this won't be a problem after switching to scuttlego.
This should be done, but won't be tackled until after we switch to scuttlego.
Needs design @Chardot
Related to #622 in part