sets up directory structure. adds amazon scraper. adds get_title, get_author, get_isbn_10, get_price methods to amazon scraper. creates book item.
adds get_shipping_weight method to amazon scraper
adds box to items. box now initializes with books as an empty array. box now has an add_book method.
refactors get_author and get_isbn_10 methods of amazon scraper to O(n)
refactors back_pooks method