CORE-3552 Update to not popup notifications on login.

Updated NotificationListView to not show notification popups on the very first fetch of unseen messages.
This will prevent old, unseen notifications from popping up every time the user refreshes their browser/session.
Also added an initial GetMessageCounts::run call to DEPresenter::initMessagePoller so that new message counts are fetched right away at login (otherwise the initial unseen count would not be fetched until after an entire poll-length of the timer elapsed).