libvirt.finish_migration is too large and not tested

[Sahid Orentino]

This method needs to be split in several small methods then each methods has to be tested.

A possible solution could be:
  * determines the disk size from instance properties
  * methods to convert disk from qcow2 to raw and raw to qcow2
  * method to resize the disk

[Openstack Gerrit (openstack-gerrit)]

Reviewed: https://review.openstack.org/67912
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=c393892e5b0ec72cc8f515c2372d149c6476768a
Submitter: Jenkins
Branch: master

commit c393892e5b0ec72cc8f515c2372d149c6476768a
Author: Sahid Orentino Ferdjaoui <email address hidden>
Date: Thu Mar 6 11:17:50 2014 +0100

    Add helper method to determine disk size from instance properties

    Add a _disk_size_from_instance method which by using the disk name
    determine the size of the disk refered in the instance properties.
    Update the method finish_migration to use this new helper.

    Change-Id: I45bd3804fdabff35189421d01a0503c886c24a4c
    Related-Bug: #1298975

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/78576
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=441f6e80a9d465bbc63d8482b3841a859ed068ab
Submitter: Jenkins
Branch: master

commit 441f6e80a9d465bbc63d8482b3841a859ed068ab
Author: Sahid Orentino Ferdjaoui <email address hidden>
Date: Thu Mar 6 11:41:27 2014 +0100

    Add helper methods to convert disk

    Add a _disk_raw_to_qcow2 and _disk_qcow2_raw methods which
    convert disk.
    Update finish_migration to use these helpers.

    Change-Id: If98f7fc04668916fda788afb65116a89463b0020
    Related-Bug: #1298975

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/78597
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=642e6acc5bf469dcf419da3bc5dce9d83aa48d6a
Submitter: Jenkins
Branch: master

commit 642e6acc5bf469dcf419da3bc5dce9d83aa48d6a
Author: Sahid Orentino Ferdjaoui <email address hidden>
Date: Tue May 27 06:23:52 2014 -0400

    libvirt: split and test finish_migration disk resize

    Adds a '_disk_resize' method to help resizing disk
    by checking and preparing the disk to be extend with disk.api.
    Update finish_migration to use this helper.

    Closes-Bug: #1298975
    Signed-off-by: Sahid Orentino Ferdjaoui <email address hidden>

    Change-Id: Iefe16915a2e657d848629d7e4a4fcf67298f913e