Fuel create partition on all disks, even if they marked as unallocoated

[Michael Kraynov]

VERSION:
  feature_groups:
    - mirantis
  production: "docker"
  release: "6.1"
  openstack_version: "2014.2.2-6.1"
  api: "1.0"
  build_number: "525"

Steps to reproduce:

1. Create environment
2. Add compute node with 2 or more disks
3. Set one disk as unallocated
4. Deploy env

Expected behavior:
Partition on this disk should not be created

Current behaviour:
Partition /dev/sdb1 is created

One more issue, if we edit disk configuration via CLI and remove all strings about one disk, then upload this yaml without any error- nothing changing, partition will be created.