Dino Dex First Refactor

Let me know when you have a few minutes.  I want to go over a few of the questions you had which I haven't yet done anything with.
You don't need an @ symbol for variables defined with `attr_accessor`. Just `weight_in_lbs = ...`. Also, change the name of the argument variable so it doesn't get shadowed by the instance variable. In general, different variables should have different names.