remove deprecated method in scheduler driver

[Yaguang Tang]

method encode_instance in scheduler driver hasn't been used after Essex, it's used to encode instance dict sended through RPC before.
we can safely remove it .

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/46413

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/46413
Committed: http://github.com/openstack/nova/commit/85cb33ffe6991398e763621a05fb290d9fa50581
Submitter: Jenkins
Branch: master

commit 85cb33ffe6991398e763621a05fb290d9fa50581
Author: Yaguang Tang <email address hidden>
Date: Fri Sep 13 12:32:30 2013 +0800

    Remove unused method in scheduler driver

    Scheduler driver code clean, remove method encode_instance in scheduler
    driver, since it's unused since Folsom.

    Fix bug #1224783

    Change-Id: I8bd7ee55a4b522d4c628c7f652833dfa20342b33

[Jiajun Liu (ljjjustin)]

since the commit had been merged, change status to 'fix commited'.