MUConnectionController: fix alert view bug on iOS 7.

Add a runloop wait inside hideConnectingView to fix
an issue where our certificate accept alert view would
be hidden (or any alert view shown almost immediately
after the "connecting" alert view).

Also, change the dismiss call for the "connecting" alert
view to dismiss the alert view with an animation. This
gives a better feel on pre-iOS 7 devices, now that we have
to perform the runloop wait anyway.