Request ClientUI.clearAlerts() or .removeAlert(something)

I think there might be something similar internally already, since the alert that shows up when you enter your password wrong goes away once you successfully sign in. It would be nice so that we can remove start-up messages after 10 or 15seconds to prevent cluttering up alerts.

Another option would be to add an argument to showAlert to specify a time after which the alert will remove itself automatically.