Assignment 3 Pull Request

Hey all!

Finished assignment 3. I'm still a little unclear on how after_save works. From the examples I found on stack overflow, I'm assuming it's a method that's called after <obj>.save, and in our case we use it to update the score count for the parent link? I left comments on what I understood for each test. Please let me know if there are any mistakes or if any improvements can be made.

As always thanks in advance for taking time to grade my work!!
-Y