ceilometer query cannot filtered by None value

[Liusheng]

ceilometer API cannot query with None value as filter value.
for example, "ceilometer meter-list" command can list all current metrics and some with user_id as "None", but we cannot use "ceilometer meter-list -q user_id=None" or "ceilometer meter-list -q user_id=null" commands to filter to get the metrics without use_id.
the others APIs is similar.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/260331

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/260331
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=bbaabaf887f1b87a23aaf3cd73b7b68ac20f13a5
Submitter: Jenkins
Branch: master

commit bbaabaf887f1b87a23aaf3cd73b7b68ac20f13a5
Author: ananya23d <email address hidden>
Date: Tue Dec 22 10:47:36 2015 +0530

    Set None explicitly to filter options.

    When user set None in query string value
    'None' was set instead of None.

    Note: This fix is for mongodb only. I will
    add another patch for other database.

    Partial-Bug: #1388680
    Change-Id: I2f42013b9c8fb9a3af9d6366f10dd8bb3906d73a

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/275054

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/275054
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=c25c0447419e787facbec11ee96a692be589cee0
Submitter: Jenkins
Branch: master

commit c25c0447419e787facbec11ee96a692be589cee0
Author: Ananya Chatterjee <email address hidden>
Date: Tue Feb 2 12:50:07 2016 +0530

    Set None explicitly to filter options.

    When user is set to None in query, string value 'None'
    was set instead of None.

    Note: This fix is for mysql.
    Fix for mongo is provided in:
    https://review.openstack.org/#/c/260331/

    Note2: Here, test for resource_id is removed as,
    in sqlalchemy implementation, resource_id cannot be None.

    Change-Id: I4bcf9283912e857a9902c62df25d0d5090670b10
    Partial-Bug: #1388680