Port ceph-brag to Python 3 (+ small fixes)

[oprypin]

Compatibility with Python 2.6+ is kept.

Testing done:

set -o errexit
#cd src

./vstart.sh -d -n -x

for v in 2 3; do
    virtualenv --no-site-packages -p python$v venv$v
    . venv$v/bin/activate

    pip install pecan sqlalchemy requests cython

    pushd pybind/rados
        python setup.py install
    popd

    pushd brag/server
        python setup.py develop
        pecan serve config.py &
        server_pid=$!

        python setup.py test
# test_units (ceph_brag.tests.test_units.TestUnits) ... ok
# test_1_get_invalid_url_format (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_2_put (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_3_put_invalid_json (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_4_put_invalid_entries_1 (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_5_put_incomplete_json (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_6_get (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_7_get_invalid_uuid (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_8_get_invalid_version (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_91_delete_wrong_uuid (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_92_delete (ceph_brag.tests.test_functional.TestRootController) ... ok
# test_9_delete_invalid_parameters (ceph_brag.tests.test_functional.TestRootController) ... ok
#
# ----------------------------------------------------------------------
# Ran 12 tests in 0.723s
#
# OK
    popd

    PATH=".:$PATH" brag/client/ceph-brag update-metadata --name=ceph --organization=organization --email=example@example.org --description=description --url=http://localhost:8080
    PATH=".:$PATH" brag/client/ceph-brag publish

    curl http://localhost:8080/
    echo
# [{"email": "example@example.org", "cluster_creation_date": "2016-06-30 16:02:21.857864", "cluster_name": "ceph", "num_versions": 1, "organization": "organization", "uuid": "242a16cb-c181-4a55-917a-94e9f9fd8db0"}]

    kill $server_pid

    deactivate
    rm -rf venv$v
done

The two commits related to JSON fields were required for the tests to run properly, even on Python 2.x.

This pull request does not depend on other pending changes related to Python 3 compatibility, because rados.pyx binding works fine already, and the ceph subprocess is ran using default Python.

[tchaikov]

will test it locally.

[tchaikov]

also tested locally.