callbacks.rb in activesupport-3.0.6.rc1

- old
+ new

@@ -1,4 +1,5 @@
+require 'active_support/concern'
 require 'active_support/descendants_tracker'
 require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/class/inheritable_attributes'
 require 'active_support/core_ext/kernel/reporting'
 require 'active_support/core_ext/kernel/singleton_class'