add products.txt
new file FileHelper
new test file
add test get method
modify get method
add product.java
add field and get/set method
add cartItem.java
add field and get/set method
add interface Scanner.java
add abstract medhotd
add test DataProviderTest
add test should_return_an_product_object
modify buildProduct
modify resourse file
add test should_return_a_product_list
modify getProductList
add test BarcodeScannerTest
add test should_get_a_product_when_input_an_barcode
modify getProduct