feat(format): add yaml output format

cmd/helm/list.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"fmt"
 	"os"
 
 	"github.com/codegangsta/cli"
@@ -28,6 +27,5 @@ func list(host string) error {
 	if err != nil {
 		return err
 	}
-	fmt.Println(list)
-	return nil
+	return format.YAML(list)
 }

format/messages.go

@@ -3,6 +3,8 @@ package format
 import (
 	"fmt"
 	"os"
+
+	"github.com/ghodss/yaml"
 )
 
 // This is all just placeholder.
@@ -35,3 +37,13 @@ func Warning(msg string, v ...interface{}) {
 	msg = "[Warning] " + msg + "\n"
 	fmt.Fprintf(os.Stdout, msg, v...)
 }
+
+func YAML(v interface{}) error {
+	y, err := yaml.Marshal(v)
+	if err != nil {
+		return fmt.Errorf("Failed to serialize to yaml: %s", v.(string))
+	}
+
+	Msg(string(y))
+	return nil
+}