Mms proposed updates

These are my proposed updates, mostly reflecting the things that I've been doing without documenting them. Feel free to tear them apart. I'll annotate changes that I think need explanation.
In our code, a lot of times will make a base class which has methods, and extend that. This is useful because we can do things like:

    def my_method
      raise 'Implement in subclass'
    end

Which essentially implements an interface that you can refer to when implementing a subclass. Also, you can easily add helper methods which are shared by subclasses.

Ducktyping makes sense in a few scenarios, but I don't know if it's enough to keep it in the style guide.