Add support for graceful shutdown

Fixes #1014

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

internal/cmd/install_windows.go

@@ -109,5 +109,9 @@ func getCustomServeFlags() []string {
 	if logCompress != defaultLogCompress {
 		result = append(result, "--"+logCompressFlag+"=true")
 	}
+	if graceTime != defaultGraceTime {
+		result = append(result, "--"+graceTimeFlag)
+		result = append(result, strconv.Itoa(graceTime))
+	}
 	return result
 }