The framework to deal with ctr problem
details: https://zhuanlan.zhihu.com/p/32885978
FNN's introduction and api: https://zhuanlan.zhihu.com/p/33045184
PNN's introduction and api: https://zhuanlan.zhihu.com/p/33177517
DeepFM's introduction and api: https://zhuanlan.zhihu.com/p/33479030
AFM's introduction and api: https://zhuanlan.zhihu.com/p/33540686
NFM's introduction and api: https://zhuanlan.zhihu.com/p/33587540
DCN's introduction and api: https://zhuanlan.zhihu.com/p/33619389