BigSwitch port tracking code doesn't correctly handle missing host id

[Kevin Benton]

When a port request is received from nova without the host_id portbinding information present, the BigSwitch plugin does not correctly skip the port tracking code.
This is caused by the extension framework automatically setting the host_id to an empty object.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/34958

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/34958
Committed: http://github.com/openstack/quantum/commit/a87a7c2ad0909c28f3d9d62a13cec59ee4d2e0e6
Submitter: Jenkins
Branch: master

commit a87a7c2ad0909c28f3d9d62a13cec59ee4d2e0e6
Author: Kevin Benton <email address hidden>
Date: Fri Jun 28 14:40:11 2013 -0700

    Fix case with no host_id in BigSwitch plugin

    This correctly checks for the case where nova does not
    provide the host_id in port creation/updates.

    Fixes: bug #1195903
    Change-Id: Ic0d714a3977810c6b1144c1e25488f75cc95d0f0