pass incorrect volume_size in block_device_mapping

[huangtianhua]

1. create a stack with a OS::Nova::Server resource, and the property of 'block_device_mapping' is defined as:

------
    block_device_mapping: {'device_name': 'vdb', 'snapshot_id': 9ef5496e-7426-446a-bbc8-01f84d9c9972, delete_on_termination: True}]
   ------

2. we expected to create a server, and to attach a volume(which create from the snapshot ) to the server, but heat pass incorrect bdm with volume_size(0) to novaclient, so nova doesn't create a volume:

vdb:9ef5496e-7426-446a-bbc8-01f84d9c9972:0:True,

novaclient parse the bdm and then pass the block_device_mapping to nova as following:
 "block_device_mapping": [{
 "volume_size": "0",
 "snapshot_id": "9ef5496e-7426-446a-bbc8-01f84d9c9972",
 "delete_on_termination": "True",
 "device_name": "vdb"
}]

3. It's a bug

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/103822

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/103822
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=37f98778f2c77d1c680a78bf79395c7a431ca506
Submitter: Jenkins
Branch: master

commit 37f98778f2c77d1c680a78bf79395c7a431ca506
Author: huangtianhua <email address hidden>
Date: Tue Jul 1 17:35:34 2014 +0800

    Fix pass incorrect volume_size while building bdm

    If specify device_name, snapshot_id, delete_on_termination=True
    and not specify volume_size for bdm while create a server,
    heat will pass the bdm such as {'vdd': '1234:snap:0:True'} to
    novaclient, the volume_size is incorrect,
    nova won't create a volume from the snapshot because the
    volume_size=0. If not specify volume_size, just to pass ''.

    Change-Id: Ic1407671cc7bc6695bcf8e0c9f86fbdbaf245658
    Closes-Bug: #1335728