Added test demonstrating issue #64

A directory hacked inside the distutils `EGG-INFO/scripts` metadata directory
(which can apparently happen in python 3.3 with a `__pycache__` directory)
breaks the current distutils script detection code.

Refs #64
Added fix for issue #64

I used Marius' suggestion (with one additional fix). The issue is demonstrated
by the test in @77cd8b168b5908013e72ecd810e61d5ea4ddd7c4. This commit fixes
the failing test.

Fixes #64
Added changelog entry
Improved wording
Merge pull request #67 from reinout/reinout-33-cornercase

Fix for #64: __pycache__ dir inside distutils scripts metadata directory