notifications: Add notifications for warnings/errors
Per @guido.gunther 's comment here:
mid term we want to bubble up errors to the user so things don't go wrong silently (people tend to get mad when they send messages that don't arrive, etc and networks are by nature unreliable). There's also lots of places that print a warning to the log but don't show anything to the user, it might make sense to bubble up some of them to the user as well but we can look at that once this is in.
It would be nice to make some sort of user notification so of SMS/MMS/other protocols have errors sending/receiving, the user an be notified via the GUI so they can take action versus not know about the error.