Prevent running the demo with sudo

[chrisburr]

It shouldn't be necessary to use sudo to run the and I think we should just outright forbid it and exit if sudo is being used.

[chaen]

Although not necessary, I really don't think we should forbid it. I am all in favor of making things easy for people, but I hate taking people by the hand so much. If somebody has enough karma to run sudo without thinking, that person should not have sudo.