added pidfile option for wwclient

cmd/wwclient/main.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/hpcng/warewulf/internal/app/wwclient"
+)
+
+func main() {
+
+	root := wwclient.GetRootCommand()
+
+	err := root.Execute()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "ERROR: %s\n", err)
+		if wwclient.DebugFlag {
+			fmt.Printf("\nSTACK TRACE: %+v\n", err)
+		}
+		os.Exit(255)
+	}
+}