allow kubectl subcmds to process multiple resources

- use resource.Visit() to recursively process resources, as well as, aggregate
errors where possible

hack/testdata/recursive/rc/busybox.yaml

@@ -0,0 +1,24 @@
+apiVersion: v1
+kind: ReplicationController
+metadata:
+  name: busybox0
+  labels:
+    app: busybox0
+spec:
+  replicas: 1
+  selector:
+    app: busybox0
+  template:
+    metadata:
+      name: busybox0
+      labels:
+        app: busybox0
+    spec:
+      containers:
+      - image: busybox
+        command:
+          - sleep
+          - "3600"
+        imagePullPolicy: IfNotPresent
+        name: busybox
+      restartPolicy: Always

hack/testdata/recursive/rc/rc/busybox-broken.yaml

@@ -0,0 +1,24 @@
+apiVersion: v1
+ind: ReplicationController
+metadata:
+  name: busybox2
+  labels:
+    app: busybox2
+spec:
+  replicas: 1
+  selector:
+    app: busybox2
+  template:
+    metadata:
+      name: busybox2
+      labels:
+        app: busybox2
+    spec:
+      containers:
+      - image: busybox
+        command:
+          - sleep
+          - "3600"
+        imagePullPolicy: IfNotPresent
+        name: busybox
+      restartPolicy: Always

hack/testdata/recursive/rc/rc/busybox.yaml

@@ -0,0 +1,24 @@
+apiVersion: v1
+kind: ReplicationController
+metadata:
+  name: busybox1
+  labels:
+    app: busybox1
+spec:
+  replicas: 1
+  selector:
+    app: busybox1
+  template:
+    metadata:
+      name: busybox1
+      labels:
+        app: busybox1
+    spec:
+      containers:
+      - image: busybox
+        command:
+          - sleep
+          - "3600"
+        imagePullPolicy: IfNotPresent
+        name: busybox
+      restartPolicy: Always