My argument is that it doesn't make sense. The new lockfile is going to have to be a major version bump anyway. The berksfile is not responsible for "installing" anything. Therefore, it should not have an `install` method. The berksfile is just a collection of sources and definitions. Having an `#install` method doesn't make a whole lot of sense. 

I'm also not entirely removing the functionality - I'm proxying to the appropiate class with a deprecation warning.