{
    "os-attach": {
        "instance_uuid": "95D9EF50-507D-11E5-B970-0800200C9A66",
        "host_name": "cinder-2",
        "mountpoint": "/dev/vdc"
    }
}

{
    "os-attach": {
        "instance_uuid": "95D9EF50-507D-11E5-B970-0800200C9A66",
        "mountpoint": "/dev/vdc"
    }
}

Remove "host_name" in os_attach parameter
Remove "host_name" in os_attach parameter

It cannot be in the same request with "instance_uuid"

Change-Id: I181a2bedcf57d303c924a53d47d62305ef3af678
Closes-Bug: #1515614
