Deliverymethod

When trying to set a custom action manager in the config
````
action_manager: milia_timeline.manager.action_manager
````
I got the error 
````'The service definition "milia_timeline.manager.action_manager" does not exist.````

The cause of the error is
https://github.com/stephpy/TimelineBundle/blob/master/DependencyInjection/SpyTimelineExtension.php#L67

The quick fix you mentioned in (similar issue) https://github.com/stephpy/TimelineBundle/issues/112#issuecomment-22436826 does not work for me

This pull request moves that method call to a compiler pass.