Update filesystem.py

fix WindowsError: [Error 32].
because must close the file before rename the file in window system.
bump for version 0.3.4
Fix Requests 2, Version Bump to 0.3.5

This fixes a compatiblity issue with the new version of requests.
Bumps the release version to 0.3.5, and closes #39.
Merge pull request #1 from kevin1024/master

合并