[fuel-devops-3] Backing store doesn't work in teamplate

[Dmitry Tyzhnenko]

Fuel devops does not support the backing store for volumes in template. If set path to qcow image, will get error backing store is not Volume object.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/333224

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/333224
Committed: https://git.openstack.org/cgit/openstack/fuel-devops/commit/?id=5ee9f89bced24ec16b97ed80d8b8dae17a673ae3
Submitter: Jenkins
Branch: master

commit 5ee9f89bced24ec16b97ed80d8b8dae17a673ae3
Author: Anton Studenov <email address hidden>
Date: Mon Jul 18 12:44:30 2016 +0300

    Add support of backing store volumes from templates

    - Added 'group_volumes' section under group in templates. Now volumes
      can be defined there and then used as backing_store for node volumes.
      Example:
          groups:
            - name: default
              driver:
                 name: devops.driver.libvirt
              group_volumes:
               - name: parent
                 source_image: !os_env CENTOS_CLOUD_IMAGE_PATH
                 format: qcow2
              nodes:
               - name: admin
                 role: centos_master
                 params:
                   vcpu: !os_env ADMIN_NODE_CPU, 2
                   memory: !os_env ADMIN_NODE_MEMORY, 3072
                   boot:
                     - hd
                     - cdrom
                   volumes:
                    - name: system
                      backing_store: parent
                      format: qcow2
                      capacity: 50
                    - name: iso
                      capacity: 1
                      format: raw
                      device: cdrom
                      bus: ide

    - Added group foreign key field to Volume
    - Fixed issues with capacity being converted to gigabytes twice
    - Deprecated LibvirtVolume.fill_from_exist()
    - Deprecated LibvirtVolume.volume_get_predefined()
    - Added unit tests for backing_store and ParamLinkField

    Change-Id: Iccadafea7e5442446fedddef2b4682f8f083bf8e
    Closes-Bug: #1595442