Change which Server methods need to acquire RLock
Update comments
Fixes #14. New feature: command console
Enter commands via stdin to start / stop servers, get server status,
and stop wrapper.
Fixes #1. Eliminated calls to pgrep and pkill.
Third-party module psutil is now used for all interactions with
system processes, install of calling the UNIX commands pgrep and pkill.
This increases platform-independence.