Removed search bar to conform with specs.
Added publisher into Song.java.
Change cart.java to implement Serializable.
Add getPublisher().
Added cart.jsp.
Factorised features into functions.
Added implementation for adding items to cart.
Display message when cart is empty else show table of purchases.
Added check out button. And added if statements to display the items
that are duplicated.
Added confirm.jsp
Added end.jsp and functionality to remove, checkout and ending to
ControlServlet.java
Centered things.