Use six library to ensure pycaffe.py python3 compliance

[ttdt]

By replacing itervalues, next and iteritems with six library functions, pycaffe.py is now python3 compliant.

[seanbell]

You can use // to get integer divide for both python2 and python3.

[ttdt]

Use // for integer division (python2 and python3 compliant)

[ttdt]

CI build fails because of random 404 on package download from repo.continuum.io: https://repo.continuum.io/pkgs/free/linux-64/setuptools-20.1.1-py35_0.tar.bz2
I'll try again (close/reopen PR) in a few hours, hoping the bug will be fixed.

[longjon]

I guess I'd rather we make our use of six explicit by just doing import six here... I think that's how we already do it in other files, and six is pretty short, and I think it's easier to read that way.

You can also drop the comment, IMO... we all know what six does, and anyone who is not familiar with it can find out easily.

[longjon]

Looks good except as noted. We should really have tests that cover these cases...

[longjon]

Great, the diff looks good to me now. If you could clean up the history by squashing into a single commit, this will be ready for merge.

[ttdt]

PR #3746 opened with a clean history.

Edit: sorry for this mess, i reopened this one (#3716) and closed the new one (#3746).

[shelhamer]

@ttdt in the future do not close the PR, but instead update the PR by force pushing to your branch. Making new PRs adds noise to the tracker.

[longjon]

Thanks for the Python 3 update, merging!

(By the way, I think you mean "integer division" or "floor division" in the commit message (but it's not worth fixing, just a note for the future)).