clean some tests files, README and namespace in case of emptiness

README.md

@@ -87,10 +87,10 @@ configmap "django-config-g55mctg456" deleted
 ingress.extensions "my-ingress" deleted
 ```
 
-If you want to fail on untracked resources (exit status 1), you can use `-fail=true`:
+If you want to fail on untracked resources (exit status 1), you can use `-fail`:
 
 ```
-$ untrak -c untrak.yaml -fail=true
+$ untrak -c untrak.yaml -fail
 ```
 
 > **Caution**: please test this tool extensively before deleting resources. The software is provided "as is", without warranty of any kind.

example/manifests/resources_in.yaml

@@ -1,5 +1,11 @@
 ---
 apiVersion: v1
+kind: Namespace
+metadata:
+  name: app
+  namespace: app
+---
+apiVersion: v1
 kind: Service
 metadata:
   labels:

example/manifests/resources_out.yaml

@@ -79,3 +79,8 @@ spec:
           serviceName: django
           servicePort: 80
         path: /
+---
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: app

kubernetes/structs.go

@@ -7,7 +7,7 @@ import (
 // Metadata of kubernetes resource
 type Metadata struct {
 	Name      string `yaml:"name"`
-	Namespace string `yaml:"namespace"`
+	Namespace string `yaml:"namespace,omitempty"`
 }
 
 // Resource is a minimal description of a kubernetes object