Add extra unit test case for more than 1 ephemeral disk in BDM

[Thang Pham]

There was a comment on https://review.openstack.org/#/c/90583/ (after it was approved for merge) to add an extra test case to handle more than 1 ephemeral disk, as well as correct a comment in the code to be more accurate. The purpose of this bug is to add the extra test case for _get_instance_block_device_info to test more than 1 ephemeral disk and correct one of the comments in _get_instance_block_device_info.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/92754

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/92754
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=524ee4913d9015c2893cca69cefbc80fbe6878bb
Submitter: Jenkins
Branch: master

commit 524ee4913d9015c2893cca69cefbc80fbe6878bb
Author: Thang Pham <email address hidden>
Date: Wed May 7 22:17:29 2014 -0400

    Unit test case for more than 1 ephemeral disks in BDM

    The following patch modifies the test case for
    _get_instance_block_device_info to handle more than 1 ephemeral
    disks in the BDM. This is to address one of the comments made
    in https://review.openstack.org/#/c/90583/ after it was already
    approved for merger. This patch also corrects a comment in
    _get_instance_block_device_info to be more accurate.

    Change-Id: I11e97f2e2ef999fa08af1693483d56bf8ad0e556
    Closes-Bug: #1317321