Fix race conditions when transitioning multiple alerts
Fix race conditions when transitioning multiple alerts

When presenting or dismissing alerts at just the right times, SDCAlertViewCoordinator could get in a bad state in which it would dismiss old alerts and not show new ones. This commit should fix that issue.

badoo/SDCAlertView,DeskConnect/SDCAlertView,sberrevoets/SDCAlertView,DeskConnect/SDCAlertView,winkapp/SDCAlertView,HuylensHu/SDCAlertView,Wurrly/SDCAlertView,adamkaplan/SDCAlertView,Nykho/SDCAlertView,sberrevoets/SDCAlertView