metadata start with db connections

[yong sheng gong]

metadata agent should not try to connect db since it does not need db connections at all

$ neutron-metadata-agent --config-file /etc/neutron/neutron.conf --config-file /etc/neutron/metadata_agent.ini

2015-02-26 17:06:09.768 3045 WARNING oslo_db.sqlalchemy.session [-] SQL connection failed. 10 attempts left.
10.16.91.1:5672

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/159365

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/159365
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=458ff52c61ce7b6755df56fc2a940e4f04a6170b
Submitter: Jenkins
Branch: master

commit 458ff52c61ce7b6755df56fc2a940e4f04a6170b
Author: gong yong sheng <[e-mail]>
Date: Thu Feb 26 16:09:54 2015 +0800

    Start metadata agent without trying to connect db

    We set conf.database.connection into empty in agent,
    and tell wsgi does not to connect db in this case.

    Change-Id: Icb83157ef6f1157068f3d4238b946fdbb890083f
    Closes-bug: #1425844