property_naming.id is not used? Property way to override the naming strategy

[weaverryan]

Hi guys!

I assumed the property_naming.id configuration parameter was a service id that you could pass to override the default naming strategy.

But actually, it looks like this value is never used (no id key is ever looked at for property_naming: https://github.com/schmittjoh/JMSSerializerBundle/blob/master/DependencyInjection/JMSSerializerExtension.php#L47).

Am I reading this correctly? Is there another way to override the naming strategy? If this was just overlooked at the property_naming.id should work as I described above, I'm happy to make a PR.

Thanks!