Demo perform not well when rotate

[zzyyzz1992]

In the branch of Swift 2.0 's demo,
When rotate the screen, the camera view will not fill the screen, and the direction won't change correspondingly.
在Swift2.0分支的demo中，
当旋转屏幕时，相机视图不会填满屏幕，同时显示的方向也没有对应地改变。