Add a generic Handler interface and change the RequestHandler to be a…

… child interface of the generic one.

rx-netty/src/main/java/io/reactivex/netty/channel/Handler.java

@@ -0,0 +1,10 @@
+package io.reactivex.netty.channel;
+
+
+import rx.Observable;
+
+public interface Handler<IN, OUT> {
+
+    Observable<Void> handle(IN input, OUT output);
+
+}

rx-netty/src/main/java/io/reactivex/netty/protocol/http/server/RequestHandler.java

@@ -15,12 +15,13 @@
  */
 package io.reactivex.netty.protocol.http.server;
 
+import io.reactivex.netty.channel.Handler;
 import rx.Observable;
 
 /**
  * @author Nitesh Kant
  */
-public interface RequestHandler<I, O> {
+public interface RequestHandler<I, O> extends Handler<HttpServerRequest<I>, HttpServerResponse<O>> {
 
     Observable<Void> handle(HttpServerRequest<I> request, HttpServerResponse<O> response);