Revamp the examples

[NiteshKant]

There are the following issues with the examples:

• There is little documentation on what they do.
• They are not categorized so anyone looking at them is overwhelmed of which one to see.
  -They do not demonstrate the best way in which things can be done and are mostly complex. eg:

RxNetty.createHttpServer(port, new RequestHandler<ByteBuf, ByteBuf>() {
            @Override
            public Observable<Void> handle(HttpServerRequest<ByteBuf> request, final HttpServerResponse<ByteBuf> response) {
                System.out.println("New request recieved");
                System.out.println(request.getHttpMethod() + " " + request.getUri() + ' ' + request.getHttpVersion());
                for (Map.Entry<String, String> header : request.getHeaders().entries()) {
                    System.out.println(header.getKey() + ": " + header.getValue());
                }

                return request.getContent().materialize()
                              .flatMap(new Func1<Notification<ByteBuf>, Observable<Void>>() {
                                  @Override
                                  public Observable<Void> call(Notification<ByteBuf> notification) {
                                      if (notification.isOnCompleted()) {
                                          return response.writeStringAndFlush("Welcome!!!");
                                      } else if (notification.isOnError()) {
                                          return Observable.error(notification.getThrowable());
                                      } else {
                                          ByteBuf next = notification.getValue();
                                          System.out.println(next.toString(Charset.defaultCharset()));
                                          return Observable.empty();
                                      }
                                  }
                              });
            }
        }).startAndWait();

The above is a Http Welcome server and is certainly overly complex. This gives people an impression that its too complex to write anything in RxNetty.

• There are groovy and java examples and most of the times they are out of sync. This is a maintenance tax as they demonstrate mostly the same scenario.
• There is no validation for these examples with every build so they can just be broken.

I propose the following changes:

• Remove the groovy examples as they do not do anything different.
• Create sub-packages for different examples. eg: http, sse, udp, tcp.
• Provide a very simple Hello World example for all transports.
• Provide a README for every sub-package and give an idea about what each example does.
• Add a simple validator with each test (client & server pair) that makes sure that we validate that the examples are fine on each build.

[NiteshKant]

Pull request #142 addressed all these issues.