Ticket #3073: urar helper: fix handling filenames with spaces for unrar v5.

Extfs urar helper doesn't allow to see the whole filename if it
contains spaces and is unpacked by unrar v5. This commit should fix that.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '3073_urar5_spaces'

* 3073_urar5_spaces:
  Ticket #3073: urar helper: fix handling filenames with spaces for unrar v5.