Patch sortable to fix reinitialization errors (and memory leaks)

Refs johnny/jquery-sortable#122

Author: daftspunk

assets/ui/vendor/sortable/jquery-sortable.js

@@ -631,6 +631,10 @@
           return val != that
         })
 
+      // See https://github.com/johnny/jquery-sortable/pull/122
+      if(this.group)
+        this.group._destroy()
+
       $.each(this.items || [], function(){
         $.removeData(this, subContainerKey)
       })