We should pin oslo version in requirements.txt

[Tatyanka]

In some env we have oslo.i18n with version installed, so it we run tests there we faced with :
Traceback (most recent call last):
 File "fuelweb_test/run_tests.py", line 168, in <module>
   import_tests()
 File "fuelweb_test/run_tests.py", line 45, in import_tests
   from tests import test_backup_restore # noqa
 File "/home/jenkins/workspace/systest/master/fuelweb_test/tests/test_backup_restore.py", line 21, in <module>
   from fuelweb_test.helpers import os_actions
 File "/home/jenkins/workspace/systest/master/fuelweb_test/helpers/os_actions.py", line 22, in <module>
   from fuelweb_test.helpers import common
 File "/home/jenkins/workspace/systest/master/fuelweb_test/helpers/common.py", line 28, in <module>
   import neutronclient.v2_0.client as neutronclient
 File "/home/jenkins/venv-nailgun-tests-2.9/local/lib/python2.7/site-packages/neutronclient/v2_0/client.py", line 26, in <module>
   from neutronclient.​i18n import ​
 File "/home/jenkins/venv-nailgun-tests-2.9/local/lib/python2.7/site-packages/neutronclient/_i18n.py", line 24, in <module>
   _C = _translators.contextual_form
AttributeError: 'TranslatorFactory' object has no attribute 'contextual_form'

Caused by:
https://bugs.launchpad.net/oslo.service/+bug/1525992

after pip install oslo.i18n --upgrade all works as expected

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/266880
Committed: https://git.openstack.org/cgit/openstack/fuel-qa/commit/?id=c0400bae919bbc5b053bb263051997b5a95f5234
Submitter: Jenkins
Branch: master

commit c0400bae919bbc5b053bb263051997b5a95f5234
Author: Tatyana Leontovich <email address hidden>
Date: Wed Jan 13 14:47:55 2016 +0200

    Add oslo.in18 into requirements

    Closes-Bug: #1533672
    Change-Id: I5c3a56713d2588cde588aec95768b13100a06fec

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/8.0
Review: https://review.openstack.org/268905

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/268909
Committed: https://git.openstack.org/cgit/openstack/fuel-qa/commit/?id=2deb011733bef17bb0e33755ffcb6aa160bb7f26
Submitter: Jenkins
Branch: stable/8.0

commit 2deb011733bef17bb0e33755ffcb6aa160bb7f26
Author: Tatyana Leontovich <email address hidden>
Date: Mon Jan 18 09:56:24 2016 +0200

    Pin upper bound for neutronclient

    Change-Id: I41d121bac94cc8ad7ee3bfaa3169e4747754b588
    Related-Bug: #1533203
    Related-Bug: #1533672

[OpenStack Infra (hudson-openstack)]

Change abandoned by tatyana-leontovich (<email address hidden>) on branch: stable/8.0
Review: https://review.openstack.org/268905
Reason: Was fixed by set upper bound for neutronclient