feat(list): reordering scrolls page, reordering performance better

Fixes #521. Reordering now uses webkitTransform instead of
element.style.left.  Additionally, as you drag the drag-element to the
top or bottom of the scroll-area, it will scroll it up or down as
allowed.

Refactors necessary: Common code from `<content>` and `<scroll>` moved
into js/ext/angular/controllers/ionicScrollController.  Then `<content>`
and `<scroll>` expose the controller, and `<list>` can require it.

`<list>` then uses the controller (if exists) to pass the scrollView and
scrollEl to ReorderDrag, and ReorderDrag uses that to scroll.

Additionally, js/ext/angular/test/controller/ionicScrollController tests
much functionality that was untested before.

js/ext/angular/src/controller/ionicScrollController.js

@@ -0,0 +1,44 @@
+(function() {
+'use strict';
+
+angular.module('ionic.ui.scroll')
+
+.controller('$ionicScroll', ['$scope', 'scrollViewOptions', '$timeout',
+                     function($scope,   scrollViewOptions,   $timeout) {
+
+  scrollViewOptions.bouncing = angular.isDefined(scrollViewOptions.bouncing) ?
+    scrollViewOptions.bouncing :
+    !ionic.Platform.isAndroid();
+
+  var element = this.element = scrollViewOptions.el;
+  var refresher = this.refresher = element.querySelector('.scroll-refresher');
+  var scrollView = this.scrollView = new ionic.views.Scroll(scrollViewOptions);
+
+  this.$element = angular.element(element);
+
+  //Attach self to element as a controller so other directives can require this controller
+  //through `require: '$ionicScroll'
+  this.$element.data('$$ionicScrollController', this);
+
+  $timeout(function() {
+    scrollView.run();
+
+    // Activate pull-to-refresh
+    if(refresher) {
+      var refresherHeight = refresher.clientHeight || 0;
+      scrollView.activatePullToRefresh(refresherHeight, function() {
+        refresher.classList.add('active');
+      }, function() {
+        refresher.classList.remove('refreshing');
+        refresher.classList.remove('active');
+      }, function() {
+        refresher.classList.add('refreshing');
+        $scope.onRefresh && $scope.onRefresh();
+        $scope.$parent.$broadcast('scroll.onRefresh');
+      });
+    }
+  });
+
+}]);
+
+})();