rails g resource Comment author:string content:text article:references
Getting started with the Comment model.

- Generating a resource (or, presumably, scaffold) dependent on another does not nest the routes of the dependent within its dependency. Manually fixed in config/routes.rb
- Schema updated with "comments" table
- Comments factory data values reworked, just because.
- First baby Comment specs, verifying that the Comment can be instantiated, and than a Comment without an article ID is invalid.
- Simple fix to Comment model to require the article ID to be present, which lets us pass the second new spec.

Additional note: I did further research on FactoryGirl and relations. Back in the primordial mists of time, say three weeks ago, I was considering switching to Machinist (https://github.com/notahat/machinist) because of its reputedly superior support for stubbing relations. I've come across a couple of resources that helped me understand how to do this sanely in FG, which speeds up even these trivial specs by an order of 3 or so.