[noodle] Add a larger interface for different types of http.FileSystem implementation

[at15]

Except Open, I want to have handy method to get content of a file directly https://github.com/GeertJohan/go.rice#package-usage, maybe a Tree method, serve http file etc.

// find a rice.Box
templateBox, err := rice.FindBox("example-templates")
if err != nil {
	log.Fatal(err)
}
// get file contents as string
templateString, err := templateBox.String("message.tmpl")
if err != nil {
	log.Fatal(err)
}