Phpdoc now same as actual return type.

Hey there Michael,

thanks for your efforts I love the lib (although I'm fighting with serializing all the custom collections). Had a minor annoyance with my IDE due to wrong PHPDoc. Easy fix.

Cheers,
Michael.

![wrong-return-type](https://cloud.githubusercontent.com/assets/2168701/3670863/fc1282ec-1248-11e4-967b-c8af5069ae05.png)