code: function addClassInView(config) {
    var selector = config.selector || InViewClassAdder.DefaultConfig.selector;
    var className = config.className || InViewClassAdder.DefaultConfig.className;
    var delay = config.delay || InViewClassAdder.DefaultConfig.delay;
    var fromTop = config.fromTop || InViewClassAdder.DefaultConfig.fromTop;
    var offset = config.offset;
    var classAdder = new InViewClassAdder(selector, className, offset, delay, fromTop);
    classAdder.onScroll();
    scrolldelegator.addDelegate(classAdder);
    scrolldelegator.start();
  }
docs: Adds a class to elements when they become visible in the viewport.
  @param {Object} config Config object. Properties are:
  selector: The selector to query elements to act upon.
  className: The class name to add when elements come in view.
  offset (optional): Offset to apply when checking if the element is in
  view.
  delay (optional): A list of a maximum and minimum delay to apply the new
  class. For example, a delay of [200, 500] will apply the new class
  at a random time between 200ms and 500ms. This can be used to, for
  example, playfully transition new elements on screen as they enter
  the viewport.