Fix dataset for test_cppschema

Test dataset contained json files that were wrongly treated as invalid.
A schema against which files are validated does not contain any required fields.

Open-webOS-DCO-1.0-Signed-off-by: Alekseyev Oleksandr <oalekseyev@luxoft.com>

Change-Id: I1b674d0e3875115df9b223003943704d4ed0e986