oslo.serialization should be moved to test-requirements.txt on stable

[Matt Riedemann]

This added oslo.serialization to requirements.txt on stable/icehouse, probably to fix a gate blocker:

https://review.openstack.org/#/c/128850/

And that was cherry picked to stable/juno:

https://review.openstack.org/#/c/129170/

Those should be in test-requirements.txt since it's a testing requirement for master keystoneclient and stable keystone. The keystone code on stable/juno and stable/icehouse doesn't directly use oslo.serialization so it shouldn't be in requirements.txt.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/165894

[Matt Riedemann (mriedem)]

Looks like the requirement is no longer needed given how the tests were changed to run in a venv:

https://review.openstack.org/#/q/I079fa77501b8987a4724d03a792b084a6d853e21,n,z

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/icehouse
Review: https://review.openstack.org/165928

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/165928
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=e6eba4bf152c98dd1ff22125ec167ca59ba1ee4e
Submitter: Jenkins
Branch: stable/icehouse

commit e6eba4bf152c98dd1ff22125ec167ca59ba1ee4e
Author: Matt Riedemann <email address hidden>
Date: Fri Apr 10 08:47:52 2015 -0700

    Remove oslo.serialization from requirements.txt

    Change I00f66b0f3c8e9f688429ee78bd51608a4dcac140 added
    oslo.serialization to requirements.txt on stable to unwedge the gate due
    to keystone on stable testing against master level keystoneclient which
    required oslo.serialization.

    Later, change I079fa77501b8987a4724d03a792b084a6d853e21 fixed the
    testing problem by running the tests in a venv, so we can just
    remove oslo.serialization from keystone's requirements.txt now.

    Closes-Bug: #1434152

    Change-Id: I224a3652fba170da34da9935e6f8b4a161a856d2

[OpenStack Infra (hudson-openstack)]

Change abandoned by Matt Riedemann (<email address hidden>) on branch: stable/juno
Review: https://review.openstack.org/165894
Reason: meh