EZP-23355 Add a getter for wrappedUser property in UserWrapper

Implements https://jira.ez.no/browse/EZP-23355

This comes from a post i wrote in the forums http://share.ez.no/forums/ez-publish-5-platform/security-listener-and-userwrapper

The idea is to have access to all data in the wrappedUser so this data can be used in controllers. 
Acording  to @lolautruche this new getter won't hurt