[Phaser] container에 stagger tweens 적용

this.tween = this.tweens.add({
	targets: this.container.list,
    y: 800,
    duration: 1800,
    repeat: -1, //무한 반복
    delay: function(target, targetKey, value, targetIndex, totalTargets, tween) {
    	return targetIndex*180;
    }
})