After deploying to heroku, it shouldn't show 404

[olasitarska]

Let's move deploy one step further or at least put some warning and direct people to admin

[bmispelon]

I think the approach outlined in #208 would work better.

I like having the deploy chapter early on because if something goes wrong, it gives the coach some time to figure it out before the attendee leaves the workshop with a website that's not actually on the web.