zdtm: print test dir, dump and restore path (if any) in case of error

v7: cosmetic chages due to public pressure

v6: silly "/" miss fixed

v5: it finally workks as expected

v4: fixed wrong error print after successfull  run on all zdtm tests

v3: spaces removed

v2: print test output file path  (if present)

Print dump and restore file in case of running all tests suit.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Andrey Vagin <avagin@gmail.com>