Update runscript.py to work on Python 3.4 withouyt __init__.py files

Doesn't work on Python 3.4 with imp module (deprecated). Replaced with importlib as recommeded by the Python documentation. 

**IMPORTANT**: It failed to function with imp because I don't have __init__.py files in my modules.

I don't really know how to test for the python version and since when this new syntax is preferred. I can only say that it would be great if you could implement this for python version 3.4 (maybe even 3.3 ?).