why return batch2d in inflate_batch_norm()?

 Hi,xiaolong,

Thanks for your appealing work. When you inflating the ResNet2d into ResNet3d, I noticed that you returned the `batch2d` object in [>>inflate_batch_norm()<<](https://github.com/xiaolonw/TimeCycle/blob/master/models/videos/inflate.py#L55-#L63) function.  Shouldn't it return the `batch3d`? 