added ADF JsonDirect/string test case
added ADF JsonDirect/string test case

deaktator/vowpal_wabbit,deaktator/vowpal_wabbit,deaktator/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,hal3/vowpal_wabbit,deaktator/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,deaktator/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,deaktator/vowpal_wabbit,deaktator/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,hal3/vowpal_wabbit,hal3/vowpal_wabbit,deaktator/vowpal_wabbit,deaktator/vowpal_wabbit,hal3/vowpal_wabbit,deaktator/vowpal_wabbit,hal3/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,hal3/vowpal_wabbit,hal3/vowpal_wabbit,hal3/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,hal3/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,jon-morra-zefr/vowpal_wabbit,hal3/vowpal_wabbit,deaktator/vowpal_wabbit,hal3/vowpal_wabbit