Set booking slot as 0 if the day is holiday (#164)

열린옷장 휴무일(일, 월요일)일 경우 슬롯을 0으로 강제합니다.
Merge pull request #179 from opencloset/feature/#164-zero-booking-slot-for-holiday

Set booking slot as 0 if the day is holiday (#164)

closes #164