Added two "property" PHPDoc tags

I added two [@property](http://www.phpdoc.org/docs/latest/references/phpdoc/tags/property.html) [PHPDoc](http://www.phpdoc.org/) tags to correct two [PhpStorm](https://www.jetbrains.com/phpstorm/) inspection warnings.

### Before

![before](https://cloud.githubusercontent.com/assets/2417752/5025952/f3c7a714-6b1e-11e4-8be7-378f55e643e8.png)

### After

![after](https://cloud.githubusercontent.com/assets/2417752/5025951/f3c70fe8-6b1e-11e4-9801-93491317ab64.png)