Python 3 compatibility of Ceph CLI

[oprypin]

This replaces tabs with whitespace, fixes syntax and builtins (most controversial change would be .iteritems() -> .items() but should be fine).

There was also one bug with the validity check that was undetected on Python 2.

Compatibility down to Python 2.6 remains.

[oprypin]

What happened to the check? I don't see what went wrong from the output.

[jdurgin]

The check failure is unrelated - it's one that snuck in recently and appears in the bot sometimes but has eluded manual reproduction so far.

[jdurgin]

The changes look good, nice and straightforward. Pushed to wip-ceph-argparse-py3 and will run that through the rados suite once it's built.

[oprypin]

Don't merge yet, I've discovered other needed changes when porting the ceph script. Maybe it should be one bigger pull request?

[jdurgin]

alright, sounds like a good idea to make a larger pr since the ceph_argparse tests don't cover as much as the cli tests do

[oprypin]

I continued in this pull request.

This QA suite finished successfully for me, ran like this (from src):

$ PATH="$PATH:$(readlink -f .)" PYTHON=python3 ../qa/workunits/cephtool/test.sh --asok-does-not-need-root

This needs a fresh vstart environment

It doesn't work from just the default environment, because it also needs rados and cephfs bindings built for Python 3 specifically (I put their .py/.so files right inside pybind but there is probably a better way).

[jdurgin]

lgtm, as discussed on irc we can merge this now since it doesn't break python 2, and fix any remaining python3 issues once we get python3 integration tests working