starter ruby app

[johrstrom]

With #997 I'm thinking we should get rid of the example ps app in the Ruby tutorial and make it a lot more basic. Basically the tutorial should just cover how to get a hello world application to boot up and no more. Having to maintain that app (https://github.com/OSC/ood-example-ps) has already bitten us a couple times, so let's get rid of those details.