Update vendoring

This updates the libcompose vendoring as well as a general update to
vendoring (adds the latest git commit of libcompose).

Closes https://github.com/kubernetes-incubator/kompose/issues/426
Closes https://github.com/kubernetes-incubator/kompose/issues/471

vendor/github.com/spf13/viper/viper.go

@@ -1093,9 +1093,15 @@ func (v *Viper) ReadInConfig() error {
 		return err
 	}
 
-	v.config = make(map[string]interface{})
+	config := make(map[string]interface{})
 
-	return v.unmarshalReader(bytes.NewReader(file), v.config)
+	err = v.unmarshalReader(bytes.NewReader(file), config)
+	if err != nil {
+		return err
+	}
+
+	v.config = config
+	return nil
 }
 
 // MergeInConfig merges a new configuration with an existing config.