$apply to $applyAsync

$applyAsync seem to fix the $digest in progress issue reported in #168

Author: Vic

src/ui-scroll.js

@@ -356,7 +356,7 @@ angular.module('ui.scroll', [])
           let updates = updateDOM();
 
           // We need the item bindings to be processed before we can do adjustment
-          $scope.$apply(() => $timeout(() => {
+          $scope.$applyAsync(() => $timeout(() => {
             // show elements after data binging has been done
             updates.inserted.forEach(w => w.element.removeClass('ng-hide'));
             updates.prepended.forEach(w => w.element.removeClass('ng-hide'));