Add user systemd unit and tmux start scripts.

Created by: garloff

Even with some docu.

This one was a bit of work:

• Create a tmux script that starts a tmux session and pushed some commands into it to start run_in_loop.sh which calls run_YOURCLOUD.sh which calls api_monitor.sh
• There's also a kill script that sends ^C, so cleanup can start happening.
• There is a systemd file, meant to be installed into the --user systemd logic
• And documentation that explains how to use it, including the important sudo loginctl enable-linger $USER command which I learned doing this.