Add a failing test for Topping.initialize.
created test for new topping method to include a name
added new test to check if a topping is vegetarian
added attr_accessor to the Topping class
added test to see if new Pizza accepts an array of Topping objects
added initialize method and toppings method to the Pizza class
added new test to check if a new Pizza defaults to cheese when no toppings are declared
added to initialize method to default to cheese if no toppings are declared, if toppings are declared, add those to an array of toppings