A backup of the zhuanlan App source code

Due to the copyright problem, the source code of zhuanlan app was deleted. Here is just a backup of the source code release from the developer who has already forked.
因为版权的问题，知乎专栏App的源码已经被删除了。这里的release是从之前已经fork的开发者那里fork回来，重新发布的。