Samples: score by similar os for ksm

Score each host by how many of its vms have the same
os as the requested vm.

Bug-Url: https://bugzilla.redhat.com/773338
Change-Id: Idfb359ecbd73a1f4a2520ac8a65b753449be55bd
Signed-off-by: Noam Slomianko <nslomian@redhat.com>