Netty 3.2 to 4.1

Recipes to migrate from Netty 3.2.x to 4.1.x.

Recipes

• Change MessageEvent parameter of channelRead to Object
• Migrate Channel.setReadable(boolean) to Channel.config().setAutoRead(boolean)
• Migrate StringEncoder(String) to StringEncoder(StandardCharsets)
• Remove ChannelStateEvent parameter from handler methods
• Replace Channels.fireMessageReceived(..) with ctx.fireChannelRead(e)