core: update LUN device size using getVmStats

* Handling DirecLUN disks manual resize (user invoked)
  by synchronizing LUNs device sizes upon powering up a VM.

* Similar to disk images, utilized VdsUpdateRunTimeInfo
  in order to retrieve updated information from getVmStats.

* Added buildVmLunDisksData method to VdsBrokerObjectsBuilder
  for de-serializing relevant LUNs data from getVmStats.

* For using batch update, LunDAODbFacadeImpl now extends
  MassOperationsGenericDaoDbFacade.

Note: the functionality is depended on VDSM patch -
      http://gerrit.ovirt.org/24235

Change-Id: Ie0d4d805ca333990ea1f612eb03a87f4a505f4a8
Bug-Url: https://bugzilla.redhat.com/1026868
Signed-off-by: Daniel Erez <derez@redhat.com>