Implement a user messaging/notification UI for announcements, errors

[sfoster]

We have a few places where we need to tell the user:

• Server is offline, game is not currently available
  • If there's some reason why people can't play the game right now, or they won't see their colors up on the lights, we need a way to tell them so in words.
• If the geolocation lookup comes back as being outside the playable radius, we need a way to inform the user and explain why, and what to do about it
• If the geolocation permission is denied, we need a way to inform the user why they can't play
• If the queue at the server (?) gets too long, we need to inform the user

As the game UI is full screen-ish, a banner / floating panel kind of thing might work.