[feature request] Make .set() accept objects

[Jan Dvorak]

.set() is great, but it only works for a single field. It would be great if it could also accept objects like so:

book.set({
  author: "authorId",
  title: "book title"
})

[Kelly Copley]

I'm sure this is easily implemented, but honestly I'm going to have to dig into this code a bit and then slap the shit out of myself for not commenting this when I wrote it :-P