Move CHANGELOG entry to future version

actionpack/CHANGELOG

-*Rails 3.1.0 (unreleased)*
+*Rails 3.2.0 (unreleased)*
 
 * Refactor ActionController::TestCase cookies [Andrew White]
 
@@ -18,6 +18,9 @@
   persistent between requests so if you need to manipulate the environment
   for your test you need to do it before the cookie jar is created.
 
+
+*Rails 3.1.0 (unreleased)*
+
 * Added 'ActionView::Helpers::FormHelper.fields_for_with_index', similar to fields_for but allows to have access to the current iteration index [Jorge Bejar]
 
 * Warn if we cannot verify CSRF token authenticity [José Valim]