Merge pull request #6551 from kennyj/add_entry_20120531

Add a railtie's changelog entry about runner hook.

railties/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   Add runner to Rails::Railtie as a hook called just after runner starts. *José Valim & kennyj*
+
 *   Add `/rails/info/routes` path, displays same information as `rake routes` *Richard Schneeman & Andrew White*
 
 *   Improved `rake routes` output for redirects *Łukasz Strzałkowski & Andrew White*