ChannelInboundMessageHandlerAdapter should check if message is supported before cast it

[normanmaurer]

We should do the same in ChannelInboundMessageHandlerAdapter as we do in MessageToMessageDecoder and check if the message can be handled by the handler before cast it. Otherwise its likely that you will get ClassCastExceptions if you write more then one message type (that not share the same super type) via a Channel