Migrate to python 3

[jprltsnz]

Following the process outlined in the wiki this is the issue to track progress of the python3 migration.

Current task:

• Stage1 fixes
• Stage 1 tests completed
• Stage2 fixes
• Stage2 tests completed
• Drop python2

[jprltsnz]

I am working on this for this repo.

[rlmrjmnz]

Stage 1 fixes are merged in PR #2

[jprltsnz]

@rlmrjmnz I'll answer the question you made on PR #2 here since it has more visibility

Question: how do you both are going to test this changes??? do you have think some test cases???

As you know, most of this is old code and we don't have any test cases ready. For now we will run code that depends on this and see if it breaks. This stage only make changes to printing, so we should be fine.

I have released version 0.1.0 of this code before #2 was merged, people not working on the migration and not helping to test it should pin their code to that version.

Test cases need to be made before we proceed with stage2 since that one potentially breaks stuff.