error while running python-argcomplete-check-easy-install-script on python 3.3

[AvdN]

I was not able to get completions under python 3.3 for py.test. Tracked this down to
python-argcomplete-check-easy-install-script throwing an Error:

(3_3_2)anthon@athlon64:~/src/argcomplete$ scripts/python-argcomplete-check-easy-install-script $(which tox) --verbose
Traceback (most recent call last):
File "scripts/python-argcomplete-check-easy-install-script", line 41, in
filename = pkgutil.get_loader(module_name).filename
AttributeError: 'SourceFileLoader' object has no attribute 'filename'

In 2.7.5 get_loader returns an pkgutil.ImpLoader instance in 3.3.2 this is an _frozen_importlib.SourceFileLoader

Instead of .filename the method .get_filename() should be used, this also solves issue #34 !!