Rest for beginners

Initial Draft for REST Tutorial

resolves codebar/tutorials#102

I feel like there's quite a lot to take in here, as well as quite a lot of duplication from other tutorials. I'm not sure the examples are great from a learning point of view, and I'm still to figure out if it's a good idea to attempt the "building a rest service" is a good idea.

Any editing/advice would be helpful, and I'll try and add a bit more over the next few days.