Please upadate codes for latest version of PyTorch

In file **train.py **and** train_search.py**, you need to replace this:
```
    # objs.update(loss.data[0], n)
    # top1.update(prec1.data[0], n)
    # top5.update(prec5.data[0], n)
```
to 
```
    objs.update(loss.item(), n)
    top1.update(prec1.item(), n)
    top5.update(prec5.item(), n)
```