Merge pull request #2 from IvanHaiuk/master

fixed incorrect behavior of previous element sibling SortableJS#11

Author: mig8447

knockout-sortable.js

@@ -140,7 +140,11 @@
                 // drop an item above the 3rd visible item, but the 2nd visible item
                 // has an actual index of 5.
                 if (e.item.previousElementSibling) {
-                    newIndex = to().indexOf(ko.dataFor(e.item.previousElementSibling)) + 1;
+                    newIndex = to().indexOf(ko.dataFor(e.item.previousElementSibling));
+			
+		    if (newIndex < originalIndex) {
+			newIndex++;
+		    }
                 }
 
                 // Remove sortables "unbound" element