added CreditCardService.chargeCard and test chargeCard_updates_card_if_charge_successful
added CreditCardService.chargeCard  test: chargeCard_does_not_update_card_if_charge_unsuccessful
added CreditCardService.chargeCard  test: chargeCard_ignores_charge_for_unknown_card
updated CreditCardService.execute to just call service
created creditCardService.credit
finished creditCardService.creditCard
updated CreditCommand.execute to just call service
business logic moved from Command.execute to service
removed CreditCardDao from Commands
added CommandProcessor.report unit test
implmented CreditCardService.getAllCards
comments/renames only
migrated AddCommand parsing logic to constructor so fields can be kept final.
migrated AddCommand validation logic back to processParams, but field setting still done in constructor
migrated AddCommand validation logic back to processParams, but field setting still done in constructor;
renamed processParams to be validate
made NameAmountCommand field final
Implemented NameAmountCommand.validate
tightened accessibility for command fields
migrated MIN & MAX_CARD_NUM_LENGTH to CreditCard
removed comments