IronPython 3.4 support

Hey folks !

I successfully use RBP to batch process thousands of Revit families. Thank you for sharing this project !

I hardly maintain Python 2.7 code only for this application. IronPython now supports 3.4. It would be a great leap to become compatible with the latest release of IronPython.

If you folks have a few tips to share, I may try to upgrade and to contribute it.