发现在github上有些文件没有下载项。
1.安装svn
命令：sudo apt-get install subversion
2.比如，要克隆的项目是 https://github.com/tensorflow/models/tree/master/tutorials/image/cifar10，将其改为https://github.com/tensorflow/models/trunk/tutorials/image/cifar10,
即把/tree/master/合并为/trunk/
3.命令行敲下
svn checkout https://github.com/tensorflow/models/trunk/tutorials/image/cifar10
4.在本地目录中查找生成的文件夹
