Add Python3 support

[Shyam Singh]

Currently we support only Python 2.7 and many OpenStack projects are also compatible with Python3.

Python 3 is already well supported by major Linux distributions, whereas Python 2.7 reached its end-of-life. This need to be fixed.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/queens
Review: https://review.opendev.org/728711

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/726160
Committed: https://git.openstack.org/cgit/x/group-based-policy/commit/?id=1b996593ddef6bf9759aeb676e3bd6abf9d056f9
Submitter: Zuul
Branch: master

commit 1b996593ddef6bf9759aeb676e3bd6abf9d056f9
Author: Shyam Singh <email address hidden>
Date: Thu May 7 14:18:04 2020 +0530

    Added Python3 support.

     * dict_items, dict_values, dict_keys returns view in Py3 instead of
            list so wrapped with list.
     * hashlib.md5 needs bytes data in Py3, so encoded data with 'utf-8'.
     * Replaced dict.iteritems() with dict.items().
     * Replaced dict.itervalues() with dict.values().
     * Replaced iterator.next() with next(iterator)
     * 'magicMock' and 'int' cannot be compared, so patched
            'vmware_nsxlib.v3.utils._update_max_nsgroups_criteria_tags()'
            with its return value.
     * Added zip() as a replacement of itertools.izip() in Py3.
     * Added a method to compare 2 (nested) dict or list of (nested) dict,
            since Py3 (till python3.6) dict are not ordered.
     * Added zuul python35 CI jobs.
     * Added py35 env in 'tox.ini'.
     * Added patcher.stop() in 'NsxPolicyMappingTestCase' tearDown().

    Fixes bug 1877200

    Change-Id: Id96faba6c2ecd29918bda000ac0ccbfdf988d17d

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/728711
Committed: https://git.openstack.org/cgit/x/group-based-policy/commit/?id=8d417fc59e98dcb09caed580d2aff3d3eff97630
Submitter: Zuul
Branch: stable/queens

commit 8d417fc59e98dcb09caed580d2aff3d3eff97630
Author: Shyam Singh <email address hidden>
Date: Thu May 7 14:18:04 2020 +0530

    Added Python3 support.

     * dict_items, dict_values, dict_keys returns view in Py3 instead of
            list so wrapped with list.
     * hashlib.md5 needs bytes data in Py3, so encoded data with 'utf-8'.
     * Replaced dict.iteritems() with dict.items().
     * Replaced dict.itervalues() with dict.values().
     * Replaced iterator.next() with next(iterator)
     * 'magicMock' and 'int' cannot be compared, so patched
            'vmware_nsxlib.v3.utils._update_max_nsgroups_criteria_tags()'
            with its return value.
     * Added zip() as a replacement of itertools.izip() in Py3.
     * Added a method to compare 2 (nested) dict or list of (nested) dict,
            since Py3 (till python3.6) dict are not ordered.
     * Added zuul python35 CI jobs.
     * Added py35 env in 'tox.ini'.
     * Added patcher.stop() in 'NsxPolicyMappingTestCase' tearDown().

    Fixes bug 1877200

    Change-Id: Id96faba6c2ecd29918bda000ac0ccbfdf988d17d
    (cherry picked from commit 1b996593ddef6bf9759aeb676e3bd6abf9d056f9)