Offline Status message doesn't get through when shutting down

[burdoto]

This is due to the bot requesting the last bot message every time it tries to post an update rather than keeping the most recent ID, which is too slow on shutdown.

Also, Offline messages should use a fast resolving;

• if there is no recent message ID, just send a new one
• if there is, just send the edit and call it a day
  Maybe it's not necessary to make this check after housekeeping the ID properly.