code: function BindableCollection (source) {
    BindableObject.call(this, this);
    this.source = source || [];
    this._updateInfo();
    this.bind("source", _.bind(this._onSourceChange, this));
  }
docs: Emitted when an item is removed
  @event remove
  @param {Object} item removed
   
  Emitted when items are replaced
  @event replace
  @param {Array} newItems
  @param {Array} oldItems