add a ping service (#372)

* add a ping service

* add examples and public api file

* add minecraft server ping

ping/main.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"github.com/micro/micro/v3/service"
+	"github.com/micro/micro/v3/service/logger"
+	"github.com/micro/services/ping/handler"
+	pb "github.com/micro/services/ping/proto"
+)
+
+func main() {
+	// Create service
+	srv := service.New(
+		service.Name("ping"),
+		service.Version("latest"),
+	)
+
+	// Register handler
+	pb.RegisterPingHandler(srv.Server(), new(handler.Ping))
+
+	// Run service
+	if err := srv.Run(); err != nil {
+		logger.Fatal(err)
+	}
+}