Prevent flicker when starting a drag.

Also, animate item the view to its new position when dragging.

src/com/android/launcher2/AllAppsPagedView.java

@@ -236,6 +236,10 @@ public class AllAppsPagedView extends PagedView
         return true;
     }
 
+    @Override
+    public void onDragViewVisible() {
+    }
+
     @Override
     public void onDropCompleted(View target, boolean success) {
         // close the choice action mode if we have a proper drop