lib/merge.c: fix typo in error message

Inconsistensy -> Inconsistency

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
ploop(8): lowercase uuid

Use lowercase uuid when referring to command line option.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
merge_image(): don't return -1

Use proper SYSEXIT_* codes.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
merge_image(): don't return 0 on error

If blocksize/version checks fail, don't return 0 from merge_image(),
use proper SYSEXIT_* code.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>