finish tp2

1. in Pile interface add new method
2. add PileTest class
3. add PileFactory
4. in both PileVector and PileTable :
    add new copy constructor;
    add int size();
    override equals(Object o);
    override hashCode();
finish tp2

1. in Pile interface add new method
2. add PileTest class
3. add PileFactory
4. in both PileVector and PileTable :
    add new copy constructor;
    add int size();
    override equals(Object o);
    override hashCode();