eachAddonInvoke(methodName, args) {
    this.initializeAddons();

    let invokeArguments = args || [];

    return this.addons.reduce((sum, addon) => {
      let method = addon[methodName];
      if (method) {
        let val = method.apply(addon, invokeArguments);
        if (val) {
          sum.push(val);
        }
      }
      return sum;
    }, []);
  }
Invoke the specified method for each enabled addon.

    @private
    @method eachAddonInvoke
    @param {String} methodName the method to invoke on each addon
    @param {Array} args the arguments to pass to the invoked method