Starting external otp apps

Hello, 
i'm not expierienced with CB but i noticed that there is no easy way to start external otp applications. Adding my dependency to `.app.src` or `boss.config` to applications key was not working. I don't know if there is any proper way of doing that but according to that [open issue](https://github.com/ChicagoBoss/ChicagoBoss/issues/75) there is none. 
Please let me now if there is.