Merge branch 'devel-2.1'

* devel-2.1:
  _ExecuteKVMRuntime: fix hv parameter fun
  Update FinalizeMigration docstring
  LUGrowDisk: fix operation on down instances
  Allow disk operation to act on a subset of disks
  NEWS: add release date for 2.1.3
  Bump up version for the 2.1.3 release

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>