Issue #1647 NUX: Content on create account screen is shifted up after returning from...

... Terms of Service screen.
Issue #1647 
Because we show and hide the navigation bar when we show the TOS Web View, the view returned from self.view is shorter because the navbar animation has not completed.  I changed it to check the height of the screen since we are hiding the nav bar.
Ah I didn't think about this screen supporting portrait or iPad.  I'll add a comment and test orientation.