Run AnacondaExceptionHandler in cmdline mode
    
    cmdline mode still needs to have the exception handler run. It exits
    anaconda when there are problems, without it you can get stuck in a loop
    in the summary hub when there are incomplete spokes.
    
    This adds an interactive argument to it so that when the handler runs in
    cmdline mode it only prints out the error and calls sys.exit(1) --
    skipping the call to the superclass from meh which tries to run a UI to
    prompt for debugging.