--volatile-disk and --persistent-disk are given the same device name

When both --volatile-disk and --persistent-disk are used at the same time on CLI the corresponding disks are given the same name vdc. Then, the deployment with libvirt fails.

$ stratus-run-instance --ram 1024 --cpu 1 GuiiMg3AYfPMvyVWH242-ctLuR7 --persistent-disk 4372c700-914b-468f-88b4-b3fc18595e04 --volatile-disk 1 -vvv
Downloading from: https://marketplace.stratuslab.eu/metadata/GuiiMg3AYfPMvyVWH242-ctLuR7
Downloading from: https://marketplace.stratuslab.eu/metadata/GuiiMg3AYfPMvyVWH242-ctLuR7
Downloading from: https://marketplace.stratuslab.eu/metadata/GuiiMg3AYfPMvyVWH242-ctLuR7
Accessing storage service at: https://154.48.152.10:8445/pswd
Contacting the server with GET, at: https://154.48.152.10:8445/pswd/disks/4372c700-914b-468f-88b4-b3fc18595e04/
Received response: {'status': '200', 'content-location': 'https://154.48.152.10:8445/pswd/disks/4372c700-914b-468f-88b4-b3fc18595e04/', 'transfer-encoding': 'chunked', 'accept-ranges': 'bytes', 'vary': 'Accept-Charset, Accept-Encoding, Accept-Language, Accept', 'server': 'Restlet-Framework/2.1.4', 'date': 'Mon, 24 Feb 2014 21:55:21 GMT', 'content-type': 'application/json; charset=UTF-8'}
with content:
 {
    "uuid": "4372c700-914b-468f-88b4-b3fc18595e04",
    "tag": "pdisk_test",
    "count": "0",
    "owner": "pdisk",
    "size": "1",
    "type": "DATA_IMAGE_RAW_READ_WRITE",
    "visibility": "PUBLIC"
}

Accessing compute service at: https://154.48.152.10:2634/xmlrpc
Checking image availability.
Downloading from: https://marketplace.stratuslab.eu/metadata/GuiiMg3AYfPMvyVWH242-ctLuR7
Manifest with ID GuiiMg3AYfPMvyVWH242-ctLuR7 is available. Image locations: ['http://appliances.stratuslab.eu/images/base/CentOS-6.5-x86_64-base/1.0/CentOS-6.5-x86_64-base-1.0.img.gz']

 :::::::::::::::::::::::::
 :: Starting machine(s) ::
 :::::::::::::::::::::::::
Using VM template file: /var/share/stratuslab/vm/schema.one
 :: Starting 1 machine
on endpoint: https://154.48.152.10:2634/xmlrpc
with template:
# ---- Stratuslab VM template ----

CPU    = 1
VCPU    = 1
MEMORY = 1024
RANK = "- RUNNING_VMS"

DISK = [
source   = "https://marketplace.stratuslab.eu/metadata/GuiiMg3AYfPMvyVWH242-ctLuR7",
target   = "vda",
save     = no,
readonly = "no",
driver = "raw"
]
DISK = [
type     = swap,
size     = 1536,
target   = "vdb",
readonly = "no"
]
DISK=[
  FORMAT=ext3,
  READONLY=no,
  SAVE=no,
  SIZE=1024,
  TARGET=vdc,
  TYPE=fs ]
DISK=[
  SOURCE=pdisk:154.48.152.10:8445:4372c700-914b-468f-88b4-b3fc18595e04,
  TARGET=vdc,
  TYPE=block ]

NIC = [ network_uname=oneadmin,network = "public" ]

GRAPHICS = [
port = "-1",
type = "vnc"
]

CONTEXT = [
public_key = "ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAp0MWZef3MpLtFsgADBiR4oGpeMTMkIVWspNsEFJXPzgeCCHTwrASZRfDhDJMibfQKrO8mcC8RCAbIg8Xp/cFSC3IXdr0eskQHfkCnQ3LUtlByQDrhzCpGTzl2AcYrq+602ks73pOOkBnOnAzQQ/F7zqM9QTDyQiBffAVfM0MohfsZGk0NXAPa5ed0xNKHpDdwEIKnaEw6b15iMypiSJCk2lp7OsrRvVN3vhUHiq4urzEjphvrUeOVphG7MtNOGL2wuapwP1yVgroxx5qWvQ9uM2b56x/GJeGX2P+bJJPb0hMHAStY3Y9tNOLYQT7HwQwv2xWAvRKmay0zntt6rgHNw== skaburskask@nlhlxlx002
",

target = "hdd"
]

 :: Machine 1 (vm ID: 1108)
    Public ip: 154.48.152.197
 :: Done!

                <disk type='file' device='disk'>
                        <source file='/var/lib/one/1108/images/disk.2'/>
                        <target dev='vdc'/>
                        <driver name='qemu' type='raw' cache='default'/>
                </disk>
                <disk type='block' device='disk'>
                        <source dev='/var/lib/one/1108/images/disk.3'/>
                        <target dev='vdc'/>
                        <driver name='qemu' type='raw' cache='default'/>
                </disk>

StratusLab / client

--volatile-disk and --persistent-disk are given the same device name #119