[ZF2-273] Back out change to EventManager
[ZF2-273] Back out change to EventManager

- s/$listener/$listener->getCallback()/ -- fixes circular lookup issue
  that occurred.

MadCat34/zend-eventmanager,matwright/zend-eventmanager,ezimuel/zend-eventmanager,Maks3w/zend-eventmanager,codeliner/zend-eventmanager