Added update and delete books

![interface](https://cloud.githubusercontent.com/assets/7677641/4975546/05a19354-68eb-11e4-9915-c02a945e23aa.jpg)

@bakulinav what do you think
Can we have such method in model?
We use it only once
and it is a bit specific...

I'd like to move it into controller
Could you share you POV for this question