Clean up EHomeShell

[anton-johansson]

This class is pretty messy. As this is the first time I'm writing a raw SSH shell, the focus is more on getting things to work.

• Clean it up, separate it into separate classes, different handlers, etc.
• Write unit tests that cover the functionality of the shell.

[anton-johansson]

The shell could be extracted to a separate project (com.anton-johansson.ssh/mina-sshd-command-shell?)