about xhr content support

[rainoxu]

<div id="wrapper" ng-iscroll>
    <div id="scroller">
        <div ng-repeat="...">
            here, content loaded by xhr request. ng-scroll will run before the content render, so the scrolling does not work correctly... it needs refresh()
        </div>
    </div>
</div>

maybe we can watch dom rendering, after the content loaded, refresh the scroll to make it work correctly ~~