transform divideCartItems to private
add margin
modify craeteTable.sql
transform readFile to static
delete useless codes
modify output
rename module to model
rename Ulti to util
rename Dao to dao
move promotion and subclasses to model
rename to calculate of promotion
delete useless codes
CartItem includes Item instead of inherit Item
delete useless codes
transform get of cartItem agument
add constructor to Printer
transfer CartService to Printer
clean up import
add constructor to CartService class
transfer ItemImpl to CartService