Motivate Hartl Tutorial

[kushpatel72]

Maybe we should better explain the purpose of the Rails Tutorial in the prep work? I think telling people that the Hartl tutorial will provide a bird's eye view or Rails and give passing familiarity with different components might be helpful, vs. an expectation that they understand everything inside (as is the case with the other material).

[jeffnv]

why don't we require them to submit their final result: a working twitter clone on heroku?