Socket Echo 기능 추가

src/main/java/com/eactive/httpmockserver/socket/EchoSocketServer.java

@@ -78,7 +78,7 @@ public class EchoSocketServer {
 			workerGroup.shutdownGracefully().sync();
 			channelFuture.channel().closeFuture().sync();
 		} catch (InterruptedException e) {
-			e.printStackTrace();
+			logger.error(e.getMessage());
 		}
 	}
 }