Give RestClient examples

Hi @bblimke!

I've been working on some API wrapper stuff with webmock recently, and wanting to keep things TDD, write the specs before I actually know what responses are going to fully look like.

So I usually end up taking the stub requests from the webmock output and curling them to see what things actually look like, either with curl or Ruby scripts.

So, I thought of having an option to have a copy+pastable script to test out things immediately!

I've made a basic prototype here, I was wondering if you'd be interested in something like this in the project? If so, I'll tidy this up a bit and add some more specs. If not, I'll see if I can extend it into my own gem and keep it separate :smile: 

Thanks!