*: switch to github.com/ghodss/yaml for more consistent YAML parsing

ghodss/yaml converts from YAML to JSON before attempting to unmarshal.
This allows us to:

* Get the correct behavor when decoding base64'd []byte slices.
* Use *json.RawMessage.
* Not have to support extravagant YAML features.
* Let our structs use `json:` tags

storage/kubernetes/storage.go

@@ -34,8 +34,8 @@ const (
 
 // Config values for the Kubernetes storage type.
 type Config struct {
-	InCluster      bool   `yaml:"inCluster"`
-	KubeConfigFile string `yaml:"kubeConfigFile"`
+	InCluster      bool   `json:"inCluster"`
+	KubeConfigFile string `json:"kubeConfigFile"`
 }
 
 // Open returns a storage using Kubernetes third party resource.