create class files, add initial car class file structure

define reader and accessor items in car class
create initialize method in car class
Create file for car lot class

*set up inheritance from car
*add initalize method
begin used_car class

create inheritance reference
initialize
create a depreciation method and test it

create depreciation method to determine value
create new car-test file to check if it works
Define car_lot class

Add testing to car-test.rb
Add class variables and methods