project_id and user_id should be retrieved from context

[yuanying]

currently project_id and user_id are retrieved from auth_token_info.
but these parameters can be retrieved v3 keystone api only.
because auth_token_info is different between v2 and v3.

If you specify keystone version to v2 in config file, magnum will not work.

for example:

    [keystone_authtoken]
    auth_uri=http://192.168.11.197:5000/v2.0
    auth_version = v2

this doesn't work.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/216580

[OpenStack Infra (hudson-openstack)]

Change abandoned by LinPeiyu (<email address hidden>) on branch: master
Review: https://review.openstack.org/216580
Reason: Duplicated. see https://review.openstack.org/#/c/216132/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/216132
Committed: https://git.openstack.org/cgit/openstack/magnum/commit/?id=eff6864da95ddf38c6b64b8b69568a91907a9c27
Submitter: Jenkins
Branch: master

commit eff6864da95ddf38c6b64b8b69568a91907a9c27
Author: OTSUKA, Yuanying <email address hidden>
Date: Mon Aug 24 16:36:33 2015 +0900

    Set project_id and user_id from context directly

    Currently project_id and user_id are retrieved from auth_token_info,
    but these parameters can be retrieved from v3 keystone api only.
    Because auth_token_info is different between v2 and v3. If keystone
    version v2 is specified in the config file, magnum will not work.

    This patch uses "context.project_id" instead of
    auth_token_info['token']['project']['id'].
    Because auth_token_info['token'] is set by only keystone v3.

    Change-Id: I6982f38934c0778d9a0c4271dbe08f0758b671ad
    Closes-Bug: #1487992