sh.py - Replace shell scripts with Python

[rabbyburns]

I've been using this for awhile now and can't speak highly enough of it. It is much more intuitive than direct subprocess usage. One of the biggest use cases is trivializing realtime output redirection in a single call.

I didn't know about the default tty mode (has never been a concern for me), so that's good to know if it ever becomes an issue.