Update UserEvent.php

UserEvent should allow acces to response

[Here](https://github.com/FriendsOfSymfony/FOSUserBundle/blob/master/FOSUserEvents.php#L190) we can notice that in UserEvent should be method like `getRequest`, but there is no such method. In UserEvent we only have access to user object and request object, and [here](https://github.com/FriendsOfSymfony/FOSUserBundle/blob/master/FOSUserEvents.php#L190) we can see it. So may be UserEvent should really allow us to access response?
Merge branch 'patch-1' of github.com:RiderSx/FOSUserBundle into patch-1