Updated mumf-wishlist.php

Added user_id as foreign key
Added wishlist.class.php

Added class for CRUD events for the wishlist
Updated main.css
Updated action.php

Added cases for getting/adding/deleting wish list items.
Updated main.js

Wait for DOM to load and add wishlist button to main menu. Listen for
view all button to be clicked and fetch from server. Added display of
errors based on server response.