Add Python3 support in Tacker

[Sripriya]

OpenStack community is moving to Python 3 as Python 2.7 is nearing its end of life. See https://wiki.openstack.org/wiki/Python3

Python 3 support will help in new features development for Tacker and be beneficial for the future roadmap.

Current code needs to be analyzed and weighed in for any impact Python 3 brings. Appropriate changes needs to be done in all the 3 Tacker projects.

Gate jobs for python3 needs to be introduced as well.

[zeih (zeih)]

This patch to project-config intoduces non-voting jobs for python34 tests:

https://review.openstack.org/#/c/282634/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/293905
Committed: https://git.openstack.org/cgit/openstack/tacker/commit/?id=957e4eb62b1099357dbeb5cb0664fee732bb29d6
Submitter: Jenkins
Branch: master

commit 957e4eb62b1099357dbeb5cb0664fee732bb29d6
Author: dharmendra <email address hidden>
Date: Thu Mar 17 15:06:22 2016 +0530

    py3.x: Use six.text_type() instead of unicode()

    Python 3 doesn't support unicode(), use six.text_type instead.

    Related-Bug: #1547712
    Change-Id: I4bd774ec728fea042e64d766acb37409007aed35

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/302672
Committed: https://git.openstack.org/cgit/openstack/tacker/commit/?id=643e73095aaf7a7e4eba91c01cdfe0d1931f84e7
Submitter: Jenkins
Branch: master

commit 643e73095aaf7a7e4eba91c01cdfe0d1931f84e7
Author: dharmendra <email address hidden>
Date: Thu Apr 7 16:28:19 2016 +0530

    py3.x: Use six.iteritems for Iterable dict items.

    py3.x: Use six.iteritems for Iterable dict items instead of dict.iteritems.
    Related-Bug: #1547712

    Change-Id: I1e66c1e2a3f0235029795e48e8779229420d4821

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/309639

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/309639
Committed: https://git.openstack.org/cgit/openstack/tacker/commit/?id=4bd2313d0a73ca30ff55f650eb7e5af154fa8044
Submitter: Jenkins
Branch: master

commit 4bd2313d0a73ca30ff55f650eb7e5af154fa8044
Author: caoyue <email address hidden>
Date: Sat Apr 23 10:48:11 2016 +0800

    py3.x: Use six.iteritems for Iterable dict items.

    py3.x: Use six.iteritems for Iterable dict items instead of dict.iteritems.
    Related-Bug: #1547712

    Change-Id: I5da684a5e42793c79e2e5d5aa89ecde7db451aee

[OpenStack Infra (hudson-openstack)]

Change abandoned by Martin Oemke (<email address hidden>) on branch: master
Review: https://review.openstack.org/283235

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/377470
Committed: https://git.openstack.org/cgit/openstack/tacker/commit/?id=1543d65be376c7322aae3e813b61ca975bdb9694
Submitter: Jenkins
Branch: master

commit 1543d65be376c7322aae3e813b61ca975bdb9694
Author: Cao Xuan Hoang <email address hidden>
Date: Tue Sep 27 16:57:28 2016 +0700

    Fix LOG.warn to LOG.warning

    logging.warn is deprecated in Python 3.
    https://docs.python.org/3/library/logging.html#logging.warning

    Related-Bug: #1547712

    Change-Id: Ibe8223bc358f5806f56c44ee6bd045294d3afd8d

[Sridhar Ramaswamy (srics-r)]

Marking this resolved. Let's open specific bugs to take care of any Python3-isms.