There are now two types of "command" in spring: "application commands" (e.g. `rake`, `test`, `console`) and "client commands" (e.g. `help`, `binstub`). This file contains the application commands. But `stop` should be a client command.

You can see examples of client commands in `lib/spring/client`. You should probably extract the `server_running?` logic from the `Run` command into the superclass and reuse it in your `Stop` class. Make sense?