Netty-4.1.0.CR6 发布 Java网络服务开发框架

Netty-4.1.0.CR6 发布了，Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。

此次更新主要改进记录：

Customizable NIO and epoll select strategy (#4955 and #5044)
Deprecate WRITE_BUFFER_LOW/HIGH_WATER_MARK in favor of WRITE_BUFFER_WATER_MARK (#5060and #4858)
Change the visibility of DefaultChannelId to public (#5057)
Fix propagation of channelRegistered() event in ChannelInitializer (#4995)
Fix incorrect name encoding/decoding in DNS records (#5064)
Fix missing @Sharable annotation in MqttEncoder (#5063)
Fix the bug where epoll ET with autoRead set to false will leave data on the RECV queue (#5061)