Add POST, PUT and DELETE methods for customers

I've added a `POST`, `PUT` and a `DELETE` method for customers

![capture decran 2014-03-17 a 12 31 50](https://f.cloud.github.com/assets/103900/2435468/b8cfcc46-adc7-11e3-809b-54d48dfa5407.png)

I've also added customer addresses methods:

![capture decran 2014-03-17 a 12 31 38](https://f.cloud.github.com/assets/103900/2435471/c11afdbc-adc7-11e3-9841-581562db284c.png)