Jie Yang

In `network.py` ``` if conf.use_gpu: data_format = "NHWC" else: data_format = "NCHW" ``` I think `NCHW` is preferred for GPU, while for CPU, we should use `NHWC`.

The test has a type I error rate of α should be 9/180 = 0.05, and type II error rate of β should be 4/20 = 0.2