Allow "Timed" messages in dashboards.

mroehl

There can be extenuating circumstances in which the data behind the dashboard cannot be updated at the time the dashboard stakeholders are expecting. It would be nice to have the ability to add a "temporary" message/banner at the top of the dashboard based on a timer that can be automatically removed (expire) based on the timer (or manually removed) if the message stops applying prior to the timer running out.