Code repetition in food classes

[JoeyChenSmart]

All food classes have 2 constructors, e.g.

    public Carbohydrate(int amount) throws IllegalValueException {
        super(amount, CARBOHYDRATE_MULTIPLIER);
    }

    public Carbohydrate(String amount) throws IllegalValueException {
        this(Integer.parseInt(amount));
    }

This violates SRP since our food item is now doing parsing. Also DRY since this parsing is repeated in every class.

Note that the second constructor is only used in tests. Creation of this object during runtime will always be through a parser that uses the first constructor. We should remove the second constructor.