[REQUEST] Create the constructor Media.fromId(id)

Hi, thanks for this library. It works well.
I'd like to put media's IDs into my db and show the pictures using queries.

Now the only way is to load the whole list and then get the value with a `.where()` function.

Can you either give us a `Map` where the key is the ID or a constructor method called `Media.fromId(id)` that basically builds the Media from the id?

Thanks