Fixed issue: device rotation put always the header view on top of the web view

[giummy]

The device rotation forces a main view layout, causing the header to be located at the top of the view (y=0). I modified the method layoutSubviews of EmailView class to force an update of y coordinate on every layout call to keep the previous location in the scrollview. Moreover, I added the NSAppTransportSecurity flag to make the demo working with iOS 9+.