Make the replica transformer kind aware.

The previous implementation had a bug and poorly handled
types that should not have a `spec: replica:` field.

Documentation is updated to reflect the change in behavior,
and better highlights the cases where a patch should be
used instead of this shorthand.

pkg/transformers/config/defaultconfig/defaultconfig.go

@@ -32,6 +32,7 @@ func GetDefaultFieldSpecs() []byte {
 		[]byte(varReferenceFieldSpecs),
 		[]byte(nameReferenceFieldSpecs),
 		[]byte(imagesFieldSpecs),
+		[]byte(replicasFieldSpecs),
 	}
 	return bytes.Join(configData, []byte("\n"))
 }
@@ -47,5 +48,6 @@ func GetDefaultFieldSpecsAsMap() map[string]string {
 	result["varreference"] = varReferenceFieldSpecs
 	result["namereference"] = nameReferenceFieldSpecs
 	result["images"] = imagesFieldSpecs
+	result["replicas"] = replicasFieldSpecs
 	return result
 }

pkg/transformers/config/defaultconfig/replicas.go

@@ -0,0 +1,20 @@
+package defaultconfig
+
+const replicasFieldSpecs = `
+replicas:
+- path: spec/replicas
+  create: true
+  kind: Deployment
+
+- path: spec/replicas
+  create: true
+  kind: ReplicationController
+
+- path: spec/replicas
+  create: true
+  kind: ReplicaSet
+
+- path: spec/replicas
+  create: true
+  kind: StatefulSet
+`

pkg/transformers/config/transformerconfig.go

@@ -35,6 +35,7 @@ type TransformerConfig struct {
 	NameReference     nbrSlice `json:"nameReference,omitempty" yaml:"nameReference,omitempty"`
 	VarReference      fsSlice  `json:"varReference,omitempty" yaml:"varReference,omitempty"`
 	Images            fsSlice  `json:"images,omitempty" yaml:"images,omitempty"`
+	Replicas          fsSlice  `json:"replicas,omitempty" yaml:"replicas,omitempty"`
 }
 
 // MakeEmptyConfig returns an empty TransformerConfig object
@@ -61,6 +62,7 @@ func (t *TransformerConfig) sortFields() {
 	sort.Sort(t.NameReference)
 	sort.Sort(t.VarReference)
 	sort.Sort(t.Images)
+	sort.Sort(t.Replicas)
 }
 
 // AddPrefixFieldSpec adds a FieldSpec to NamePrefix
@@ -135,6 +137,10 @@ func (t *TransformerConfig) Merge(input *TransformerConfig) (
 	if err != nil {
 		return nil, err
 	}
+	merged.Replicas, err = t.Replicas.mergeAll(input.Replicas)
+	if err != nil {
+		return nil, err
+	}
 	merged.sortFields()
 	return merged, nil
 }