add reactive-stream support

[He-Pin]

netty/netty#3902

I think it would be nice.

I am currently using reactive-kafka to consume protobuf message,and then pumping it to graylog.

message LoggingEvent {
    required LoggingLevel level = 1;
    required string host = 2 [default = "localhost"];
    optional string source = 3;
    optional string thread = 4;
    optional string logClass = 5;
    optional int64 timestamp = 6;
    message LoggingMDCEntity{
        required string key = 1;
        required string value =2;
    }
    repeated LoggingMDCEntity mdc =7;
    optional string message = 8;
    optional string stackTrace = 9;
}



enum LoggingLevel {
    ERROR = 1;
    WARNING = 2;
    INFO = 3;
    DEBUG = 4;
}

[He-Pin]

http://reactive-streams.org/