added schedule handling in addOrder, updateOrder, and removeOrder
addOrder modifies walker availability time slot to false
updateOrder modifies original walker availability to true, then the new walker to false
removeOrder modifies original walker availability to true
added schedule handling in addOrder, updateOrder, and removeOrder
addOrder modifies walker availability time slot to false updateOrder modifies original walker availability to true, then the new walker to false removeOrder modifies original walker availability to true