Added Class definition file for Car Class

* Created car class
* Added initialize method with params
* Set instance variables to params for use in class methods
Added Car Class functions, test case

* Added car "app" to test class definition functionality
  * Added junker car class instance for testing class methods

* Added instance variable for current value
  * Fixed standard_deprec method to use car_age method
Existing car class all functional at this point!

* Fixed car class def file, all present methods currently function
* Updated app test instance to show more info
Added used car class def file

* Created used car class that inherits from car
* Added additional metrics for used cars, mileage, damages (see damage commit)
* Added internal methods:
  * To add total of damages that apply to car (as specified by user)
  * For calculating mileage depreciation
  * For adjusting current value and dealership price with these additional methods
Updated car and car app

* Added dealer markup and included in dealer price calc
* Fixed syntax for origin price in internal method calcs
* Updated attribute accessors for new calcs
Added damage class def and test "app" files

* Created damage class
* Created initialize method with repair cost and description, both to be accessible outside of damage class (for use in used car)
* Test app to add instances and test calculations for both damage app and used_car app
Created used car "app" file

* Created test file that requires both used car and damage class def files
* Added instances of damage class to use for a test instance of  used car
* Tested file and used for adjustments to used car class file
Created CarLot class def file and CarLot test "app"

* Added initialize method and created car lot app for testing class