Fix dependencies of PMML module

This refines dependencies and esp. removes the dep in dirt.

Not too happy with what ends up in the lib/ directory though, this feels so 2001.

![screen shot 2014-04-03 at 18 04 36](https://cloud.githubusercontent.com/assets/313494/2605970/32ad0e0e-bb4a-11e3-8cd9-7d36729c429e.png)