plugin worker: add admin script handler

weed/command/worker_test.go

@@ -7,7 +7,7 @@ func TestWorkerDefaultJobTypes(t *testing.T) {
 	if err != nil {
 		t.Fatalf("parsePluginWorkerJobTypes(default worker flag) err = %v", err)
 	}
-	if len(jobTypes) != 3 {
-		t.Fatalf("expected default worker job types to include 3 handlers, got %v", jobTypes)
+	if len(jobTypes) != 4 {
+		t.Fatalf("expected default worker job types to include 4 handlers, got %v", jobTypes)
 	}
 }