Update Undefined.php
Update Undefined.php

Fix the php < 5.4 compatability
localheinz/json-schema,robotdance/json-schema,siwinski/json-schema,justinrainbow/json-schema,erayd/json-schema,alecsammon/json-schema,JustTSK/json-schema,Targoniy/-json-schema-for-trip-api,siad007/json-schema,araines/json-schema,sam002/json-schema,samokspv/json-schema,ChrisTitos/json-schema,richgarrod/json-schema,JoelESvensson/json-schema-hack,edisonthk/json-schema,jojo1981/json-schema,JoelESvensson/json-schema-hack,JoelESvensson/json-schema-hack