返回304的响应中增加Content-Length值

src/org/redkale/net/http/HttpResponse.java

@@ -42,7 +42,7 @@ public class HttpResponse extends Response<HttpContext, HttpRequest> {
         public ByteBuffer[] execute(final HttpResponse response, final ByteBuffer[] buffers);
     }
 
-    private static final ByteBuffer buffer304 = ByteBuffer.wrap("HTTP/1.1 304 Not Modified\r\n\r\n".getBytes()).asReadOnlyBuffer();
+    private static final ByteBuffer buffer304 = ByteBuffer.wrap("HTTP/1.1 304 Not Modified\r\nContent-Length:0\r\n\r\n".getBytes()).asReadOnlyBuffer();
 
     private static final ByteBuffer buffer404 = ByteBuffer.wrap("HTTP/1.1 404 Not Found\r\nContent-Length:0\r\n\r\n".getBytes()).asReadOnlyBuffer();