Add liveness\readiness probe for s3 api handler on /status path

weed/s3api/s3api_status_handlers.go

@@ -0,0 +1,8 @@
+package s3api
+
+import "net/http"
+
+func (s3a *S3ApiServer) StatusHandler(w http.ResponseWriter, r *http.Request) {
+	// write out the response code and content type header
+	writeSuccessResponseEmpty(w)
+}