Python 3 migration

[solarkraft]

This one is pretty obvious: There are about 3 months left until Python 2 will be really, really, really dead for real.

[solarkraft]

I see that @zanppa has already done some migration work in 0b091dd.
A problem raised is that SOAPpy doesn't work directly with Python 3. There is a migrated version SOAPpy-py3, however the author recommends against using SoapPy at all, recommending people to use suds instead.
Maybe that'd be a good idea?

[solarkraft]

So I installed SOAPpy-py3 (pip3 install git+https://github.com/Synerty/SOAPpy-py3.git) and did some minor stuff in 0e31ef2 and 461942. Sorry about the relative mess, I'm still getting my work flow set up.

[zanppa]

I planned to migrate the library to python 3 but I didn't finish that because even though I got around using SOAPpy-py3 (if I remember correctly), there was some issues with Twisted which seemed to use tuple parameters or something. I never got around to check if there was an easy way to fix that...