Expose setter method for resource_directory

[sangio90]

Hi, Let's suppose I want to instance JasperPHP once and produce two different reports using resources located in two separated directories. At the moment I need two instances of JasperPHP, wouldn't it be better if I could choose dinamically where to look for resources? In this way I could instantiate this class only once.

The same idea could be applied to most of this class properties, but at the moment my real use case concerns resource directory.

Thanks