render/string.go
func (e *Engine) String(s string, args ...interface{}) Renderer {
	if len(args) > 0 {
		s = fmt.Sprintf(s, args...)
	}
	return stringRenderer{
		Engine: e,
		body:   s,
	}
}
func (e *Engine) String(s string, args ...interface{}) Renderer {
	if len(args) > 0 {
		s = fmt.Sprintf(s, args...)
	}
	return stringRenderer{
		Engine: e,
		body:   s,
	}
}
// String renderer that will run the string through
// the github.com/gobuffalo/plush package and return
// "text/plain" as the content type.