cs 231 FullyConnectedNets 全连接网络：
Batch Normalization =None ： 仅列出了forward的演示图
Batch Normalization = batchnorm ： forward 及backward的演示图
# -*- coding: utf-8 -*-
from builtins import range
from builtins import object
import numpy as np
from cs231n.layers import *
from cs231n.layer_utils import *
class TwoLayerNet(object):
"""
A two-layer fully-connected neural network with ReLU nonlinearity and
softmax loss that uses a modular layer design. We assume an input 
