Python 3.4 support - fix tests in circleci

[bcipolli]

#1221 gets us most of the way to Python 3.x support, but some really strange test failures in circleci. We know that nothing there breaks Py2.7 support, so I'm suggesting:

• Merge Apply python-future for Python 3.4 support #1221 , but don't advertise Python 3.x support yet.
• Rebase and begin merging other PRs
• Work on the circleci failures here.

When this PR gets merged, we can then advertise Python 3.x support.

@satra @chrisfilo @alexsavio how does that sound? I'll make y'all collaborators on my repo, so any of us can work on this PR.

[satra]

@bcipolli - could you merge master with this and push - it seems some of the merged updates are still being reflected as changes here.

[bcipolli]

@satra all done! Woohoo indeed! :)

[alexsavio]

Anything remaining here? Any tip on how to analyse the long circleci output?

[oesteban]

I think this is not necessary anymore, we are testing python 2.7, 3.4 and 3.5 on travis and running all the test workflows in circleci with 2.7 & 3.5. Feel free to reopen if we want to add tests on 3.4 for circle.