Merge branch 'devel-2.4'

* devel-2.4:
  LUInstanceCreate: fix file storage dir calculation
  Check that filestorage is enabled when requested
  Remove self.op.file_storage_dir isabs check

Conflicts:
	lib/cmdlib.py
          - use constants.DTS_FILEBASED
          - handle DT_SHARED_FILE correctly

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>