function getSlotDate(dt, minutesFromMidnight, offset) {
    return startOfDT(dt, 'day')
      .set({ minutes: minutesFromMidnight + offset })
      .toJSDate()
  }
Moved from TimeSlots.js, this method overrides the method of the same name
in the localizer.js, using moment to construct the js Date
@param {Date} dt - date to start with
@param {Number} minutesFromMidnight
@param {Number} offset
@returns {Date}