Add Python3 compatibility

[goanpeca]

So I needed to track some analytics and this library seemed to work fine except the python3 issue.

I added python3 compatibility using six, fixed the tests to run on py3 as well and fixed the code to be pep8 compliant.

I am using this in my fork now, but left this here in case the project is still supported.

Cheers

[goanpeca]

@samba any chance of getting this merged?

[samba]

@goanpeca Sorry for the late follow up.
This project is maintained by Analytics Pros, my former employer. I've contacted them to consider merging these changes, as they retain ownership and privileges to accept merges on this repository.

Thank you for this contribution, and remedying my lack of PEP-8 in the original authorship :) By visual inspection I believe the changes are sound, so I'll encourage Analytics Pros to merge these at their earliest opportunity.

[goanpeca]

@samba, 👍

[goanpeca]

@LukaData now this has conflicts, should I fix or just close the PR?

[lukaszbanasiak]

@goanpeca can you provide commit to this PR with resolved conflict?