convertDateToLocalTime (date, tz) {
		let delta_tz_offset = 0;
		let now_offset = CalendarFetcherUtils.getTimezoneOffsetFromTimezone(moment.tz.guess());
		let event_offset = CalendarFetcherUtils.getTimezoneOffsetFromTimezone(tz);
		Log.debug("date to convert=", date);
		if (Math.sign(now_offset) !== Math.sign(event_offset)) {
			delta_tz_offset = Math.abs(now_offset) + Math.abs(event_offset);
		} else {
			// signs are the same
			// if negative
			if (Math.sign(now_offset) === -1) {
				// la looking at chicago
				if (now_offset < event_offset) { // 5 -7
					delta_tz_offset = now_offset - event_offset;
				}
				else { //7 -5 , chicago looking at LA
					delta_tz_offset = event_offset - now_offset;
				}
			}
			else {
				// berlin looking at sydney
				if (now_offset < event_offset) { // 5 -7
					delta_tz_offset = event_offset - now_offset;
					Log.debug("less delta=", delta_tz_offset);
				}
				else { // 11 - 2, sydney looking at berlin
					delta_tz_offset = -(now_offset - event_offset);
					Log.debug("more delta=", delta_tz_offset);
				}
			}
		}
		const newdate = new Date(new Date(date.valueOf() + (delta_tz_offset * 60 * 1000)).getTime());
		Log.debug("modified date =", newdate);
		return newdate;
	}
convert a UTC date to local time
BEFORE calling rrule.between
@param date ti conert
				tz event is currently in
@returns updated date object