Option use_user_token is created twice

[Mike Fedosin]

In glance we have two places where we register use_user_token option:
https://github.com/openstack/glance/blob/stable/kilo/glance/common/store_utils.py#L33
https://github.com/openstack/glance/blob/stable/kilo/glance/registry/client/__init__.py#L55

oslo.config considers them as one, because they have the same name and help string, but changing help string in one of them leads to an exception DuplicateOptError: duplicate option: use_user_token

It seems that we should remove the option creation in store_utils and left only one declaration in registry client.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/189793

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/189793
Committed: https://git.openstack.org/cgit/openstack/glance/commit/?id=7e65e96ea1d8b2d7b891c9a6cfd12d504cc502b2
Submitter: Jenkins
Branch: master

commit 7e65e96ea1d8b2d7b891c9a6cfd12d504cc502b2
Author: Mike Fedosin <email address hidden>
Date: Tue Jun 9 18:53:33 2015 +0300

    Remove duplicate creation of use_user_token

    This code removes duplicate creation of the option in
    store_utils and leaves only one in registry client.

    Change-Id: Ic067094b0eb2c8803b5d0140dfae27baf72ac0e1
    Closes-Bug: #1463466