nova image create should allow properties as input

[Zhenyu Zheng]

When using nova client to create a snapshot of an instance, properties cannot be provided as input. Thus is always set as None, it should be added.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/228769

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/228769
Committed: https://git.openstack.org/cgit/openstack/python-novaclient/commit/?id=3866bfb2979b0434ae62feaf9637818447f51c12
Submitter: Jenkins
Branch: master

commit 3866bfb2979b0434ae62feaf9637818447f51c12
Author: Kevin_Zheng <email address hidden>
Date: Tue Sep 29 15:25:29 2015 +0800

    Add --metadata as optional input when do nova image-create

    Currently, when using nova image-create, we are not able to
    input metadata for the snapshot, and it is always set to be
    None.

    This patch add --metadata as an optional input when calling
    nova image-create.

    Change-Id: Ic72dc3652a77cfad099e144423302042a47f6e1e
    Closes-bug: #1500727