add service entry point to generate tar.gz file and return to caller. Use of the NamedTemporaryFile will auto cleanup.

along.

fix command error message. There are really only two arguments supported (the optional 6 had been removed, but I forgot to change the message

fix up some thumbnail issues. Also we need to manage the user permissions when we clone and delete course

plus commented out failing unit tests until I can get someone to help
debug them.