Don't add the model twice to event listeners
Don't add the model twice to event listeners

- With the recent change of refreshing the model after save both the 
`this` and `updatedModel` were the same thing. 

- This change also makes all the "after" save events more consistent 
since the arguments are all the same. 

- Finally, the previous values returned as the second argument just 
weren't very useful and the id of the inserted model is available in the 
updated model, so no data is lost.

tgriesser/bookshelf,bookshelf/bookshelf,bookshelf/bookshelf,tgriesser/bookshelf