python3 support & fix permission errors

[zeehio]

This pull request adds python3 support.

It has been tested with pyhon2.7 and python3.4.
Some minor changes for making the code more PEP8 friendly are also in the pull request.

[daniel-beck]

Sorry for the lack of the response, I only got the GitHub notifications in order fairly recently.

As to this change, it's been a long time (years, actually) since I've used this myself. It'll probably take a while longer for me to have the time to review this.

[chambm]

Just found your tool, trying to get a treemap from the output of docker diff (piped through du -ak). I had to install python27 on my Windows box to get it to work, so Python 3 support (which I already had) would be appreciated. Thanks!

[daniel-beck]

Hi, thanks for your submission and your interest in this tool. While it's not mine, and my modifications are minor at best, it's nice to see that others have the same need I had and benefit from me putting it on GitHub.

Unfortunately, that was 5+ years ago for me, and without any reason to use the tool, I don't think it makes sense for this repo to continue as is, and to accept pull requests.

For that reason, I'm closing this PR and archiving the repo. Thanks for your understanding.