A new simplified approach to showing toasts, using JDStatusBarNotification

This PR takes an alternate approach to showing toasts, using the Singleton method first suggested by @dmytro.

We have one class that contains all the info about how a toast will look. It provides a simple function that can be called from any code in order to show a toast. (OK really it's not just one function, there will probably be a few different variants of it -- we already have an async version and a sync version.)