Fix: get ranking with date, time

src/game/lib/date_util.js

@@ -0,0 +1,13 @@
+class DateUtil {
+
+	static getYYYYMMDD(date) {
+		return date.toISOString().slice(0,10);
+	}
+
+	static getHHMMSS(date) {
+		return StringUtil.getNumberStartWithZero(date.getHours(), 2) + ":"
+			+ StringUtil.getNumberStartWithZero(date.getMinutes(), 2) + ":"
+			+ StringUtil.getNumberStartWithZero(date.getSeconds(), 2);
+	}
+
+}