Changed the refreshing of the user to load the user by primary key
Changed the refreshing of the user to load the user by primary key

This fixes a security issue if the user is allowed to change his
username and enters an invalid one as this new name would be stored in
the session and used by the next request.

FriendsOfSymfony/FOSUserBundle,XWB/FOSUserBundle,XWB/FOSUserBundle