ETHREEOH-2811 : logger logs the wrong user

- now clears the NDC.

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@16973 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/security/authentication/AuthenticationUtil.java

@@ -468,6 +468,8 @@ public class AuthenticationUtil implements InitializingBean
     {
         ContextHolder.setContext(null);
         InMemoryTicketComponentImpl.clearCurrentSecurityContext();
+        
+        NDC.remove();
     }
 
     /**