Support delete multiple instance groups in one request

[Guangya Liu (Jay Lau)]

nova server-group-delete can only delete one server group per one request, it is better that we enhance this command to support delete multiple server groups in one command request.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/85577

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/85577
Committed: https://git.openstack.org/cgit/openstack/python-novaclient/commit/?id=afbf4e4be06c005dee874a15765d25870317cd3b
Submitter: Jenkins
Branch: master

commit afbf4e4be06c005dee874a15765d25870317cd3b
Author: Jay Lau <email address hidden>
Date: Sun Apr 6 13:46:53 2014 +0800

    Enable delete multiple server groups in one request

    Currently, "nova server-group-delete" can only delete one server
    group in one request, this patch was enabling nova client support
    removing multiple server groups in one request.

    Change-Id: I373151bc27cbe8617e2023ba99f6fb3f0108d592
    Closes-Bug: #1302954