Bluemix ZF2更改默认索引文件

i'm new to bluemix, and don't know how to change the default index to look to public folder of the zend application, so have a php starter build, pushed the application to server, and when i call my_url, it's showing the default index file, and when i type my_url/public it's showing the zend index page ( obviously ).I want when i type my_url/ to take me to public/ folder by deafult. So has anyone had this kind of "problem"... Searched on their forums, but there is nothing about this case... i'm new to bluemix, and don't know how to chang