Add method to list all of the current cars at the dealership
Update user interface to automatically display current cars at lot
Update car inventory
Change car storage from string into a hash. Load car hash into dealership inventory.
Add user prompt to buy or sell
Add feature to request different specs from car models
Can access information on car based on the car make
Add option to search by make, model or year
Rework how information is accessed about vehicle

* previous version was stored in separate hash that lost UsedCar class
* UsedCar class status is now preserved
Add ability to negotiate over sale price
Syntax cleanup