Python3 support

[gabriel-milan]

Implement changes originally proposed at cboone@341b232. This allows Python3 support (tested with Python 3.7.3).

[tdaff]

Thanks for all the contributions!

This fix has come up a couple of times, but I think it's not the best solution. Unfortunately I've not had the time to address it properly, but I think the decoding should be happening much earlier. I've thrown together what I think it should look like, but not tested: https://github.com/tdaff/remote_ikernel/tree/py3-encoding (ideally a lot of Py2 code could also get purged).

[gabriel-milan]

Thank you for quick response!

I've seen these changes on cboone@341b232 and it kinda worked for me. I was working on adding few features for SLURM, such as GPU allocation and partition selection (added code here gabriel-milan@becf418) but I've faced some issues with pexpect that I just can't explain. I've posted on Stackoverflow but it seems that I'll get no help there unfortunately. Do you think that this might be due to the changes on this PR?

Btw, I've tested this branch of yours without any further changes and faced the same issue I've described on Stackoverflow.