JAustin hw4 submission

I didn't manage to try the challenge problems, but I'm really proud of my value functions and search. For value, I used a call to super so that car.value and usedCar.value are actually different despite having the same name (usedCar.value calls car.value). With some help from Matt, I was able to make an (unintentionally) robust search function -- you can search by any combination of make, model, year, value, price, mileage, and damages. In fact, you can search by ANY function in the car or usedcar classes - getters and other methods all together, and by using an options hash as the argument it all fits in a couple lines of code!