F5 after removing an elf object resends the POST request (unwanted behaviour)

[Michał Martyniak]

Hotfix:

    public String removeLas(Las las) {
        katalogService.removeLas(las);
        lasy.remove(las);
        return "list_books" + "?faces-redirect=true";
    }

    public String removeElf(Elf elf) {
        katalogService.removeElf(elf);
        return "list_books" + "?faces-redirect=true";
    }