internal: Fix a severe bug with the file-system wrappers on OSX. `os.walk` is expected to support modifying its return values `dirnames` and `filenames` so that you can filter out items that need to be iterated upon. I was previously returning a different list in the wrappers, which means filtering was completely broken.

colorama==0.3.3
compressinja==0.0.2
Jinja2==2.7.3
Markdown==2.6.2
MarkupSafe==0.23
Pygments==2.0.2
pystache==0.5.4
python-dateutil==2.4.2
PyYAML==3.11
repoze.lru==0.6
smartypants==1.8.6
strict-rfc3339==0.5
textile==2.2.2
Unidecode==0.4.18
Werkzeug==0.10.4