code: function isOff () {
    debug('check if turned off')
  
    return this.getCurrentActivity()
      .then(function (activityId) {
        var off = (activityId === '-1')
        debug(off ? 'system is currently off' : 'system is currently on with activity ' + activityId)
  
        return off
      })
  }
docs: Checks if the hub has now activity turned on. This is implemented by checking the hubs current activity. If the
  activities id is equal to -1, no activity is on currently.
  
  @returns {Q.Promise}