FIX: vsm_lookup_zone_by_id, vsm_zone_get_netdevs; test added

FIX: vsm_lookup_zone_by_id, vsm_zone_get_netdevs; test added

[BUG]           Can't get return parameters from vsm_lookup_zone_by_id.
                Segfault when calling zone_get_netdevs.
[Cause]         Return type should by (siss) not ((siss)); parameters aren't set properly.
                Wrong return type in vsm_zone_get_netdevs (NetDevList instead GetNetDevAttrs).
[Solution]      Return type changed.
                Added ClientSuite/LookupZoneById, ClientSuite/ZoneGetNetdevs tests.
[Verification]  Run ClientSuite test

Change-Id: I56365571aef20ecf445b5a89b6edf94abd567a35