Fix for PanGestureCancelled state

[eugene-manaev]

Probably, there can be many other cases, which will be fix by this line of code.

Fixes issue, when you trying to dismiss NYTPhotoViewer (being landscape), which presented by portrait-only controller. In that case panGestureRecognizer.state turns to "cancelled".

If not to handle this, photo stays with the same frame as on the moment of touch cancellation. Even if you continue dragging your finger, nothing will be happened, because we lost the touch!

We should treat that state the same way as "ended", because by the fact it ended.

Can be reproduced: iOS >= 8.0

I can provide video with "steps to reproduce", if you need this.