restore lazy loading

Author: mceachen

lib/closure_tree.rb

@@ -1,6 +1,6 @@
-require 'active_record'
-require 'closure_tree/acts_as_tree'
+require 'active_support'
 
 ActiveSupport.on_load :active_record do
+  require 'closure_tree/acts_as_tree'
   ActiveRecord::Base.send :extend, ClosureTree::ActsAsTree
 end