Merge pull request #8 from eljojo/master

Failing when requesting siblings. Tests forthcoming.

Author: mceachen

lib/closure_tree/acts_as_tree.rb

@@ -120,7 +120,7 @@ def descendants
     end
 
     def self_and_siblings
-      self.class.scoped.where(:parent => parent)
+      self.class.scoped.where(:parent_id => parent)
     end
 
     def siblings