Notification Android 缺少Sound参数

文档上rest api有sound参数，Model里没有
![image](https://user-images.githubusercontent.com/38374049/81529242-03b5ab80-9391-11ea-9f75-f252ed090a38.png)
![image](https://user-images.githubusercontent.com/38374049/81529293-28aa1e80-9391-11ea-8674-ad192bdc7505.png)

只能自己加一个上去
![image](https://user-images.githubusercontent.com/38374049/81535594-aaec1000-939c-11ea-817f-db8262c78a68.png)
