Netty: provide a way to configure ChannelPipelines

[slandelle]

public interface AdditionalPipelineInitializer {
    void initPipeline(ChannelPipeline pipeline) throws Exception;
}

In NettyAsyncHttpProviderConfig:

private AdditionalPipelineInitializer httpAdditionalPipelineInitializer;
private AdditionalPipelineInitializer wsAdditionalPipelineInitializer;
private AdditionalPipelineInitializer httpsAdditionalPipelineInitializer;
private AdditionalPipelineInitializer wssAdditionalPipelineInitializer;