Add ability for notifications to specify a delay
Background
In ui#513, we want to add a new notification that is shown only to users who have installed the extension at least 24 hours ago. It would be sufficient to just have a 24 hours delay between the point at which the notification was downloaded to the point at which the notification was shown.
What to change
Provide notifications with the ability to be shown after a given delay which should support a value of 24 hours.
Edited by Thomas Greiner