HDR: only show slide animation after final shot

Also make sure to reset mBurstShotsDone to 0 after taking the
final shot for the HDR image.

Change-Id: I5cb4d5286402b577e097d57aa4cc9d850a317aef
Squashed tartfu's Camera pinch to zoom fix

Change-Id: I421f29e120de640ed47543df689a680aa2d6b7bf