models: Added models for disk hierarchy calculation
models: Added models for disk hierarchy calculation

Change-Id: I7355e568c0d6441b97be7a83a90f6d87f32b2681
Signed-off-by: Shubhendu <abf833e62503b33bb0dfae62bb381d87d91f8de1@redhat.com>

skyrings/skyring-common,skyrings/skyring-common