support NormalizeableInterface

[lsmith77]

still adjusting to how JMSSerialierBundle works, but I wonder if it would make sense to support the NormalizeableInterface in cases where its simply not feasible to use annotations, but where one doesnt want to register a filter (for whatever reason). also it would make it easier for people to migrate from the core Serializer to JMSSerializerBundle.

[lsmith77]

as discussed on IRC at least it would be good to check of an object implements the SerializationHandlerInterface and if so call serialize() directly before attempting the registered handlers. This way it would no longer be necessary to register a handler for every special case, which should help improve performance. The same applies to deserialization of course.

For example see:
https://github.com/liip/LiipHelloBundle/blob/master/Document/Article.php#L25

[lsmith77]

closing in favor of #23