title: LDAP authenticated user gets deleted from the group created in sonar for every fresh login to sonar
body: <p>Authentication for Sonar (3.5.1) with LDAP plugin (1.3-SNAPSHOT) is working fine. But the authorization for projects is not working with groups. 
  From the Admin user i am able to map the LDAP user to a group created in Sonar UI.
  But everytime the user tries to login to Sonar, the users already mapped to a group gets deleted from the group.</p>
  
  <p>Has anyone faced the same issue already? is that a problem with ldap version? or do i need to make configuration changes? </p>