jsonrpc: Add more logging to JsonRpcTests to ease debugging

Change-Id: Iee91e8bd188423e886b4179e024102adc23d33fb
Signed-off-by: Saggi Mizrahi <smizrahi@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/10255
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>