Comment 3 for bug 1562836

After deeper investigation, we found that currently devops\fuel-qa spawn 'unsuitable' VMs for multipath emulation,
so, test venv should be improver to support :

1)All slaves on 'raw' disks
2)Disable snapshoting for slaves (since raw not support snapshots
3) Add to VM xml new section :
node_xml.controller(type='scsi', model='virtio-scsi')
4) Add posibility to switch-off disk caching (under testing)