LDAP handle call should pass in referral information

Migrated from: https://tracker.clearos.com/view.php?id=903

Reported by: Peter Baldwin

The LDAP_Driver.get_ldap_handle() function needs to pass in referral information to the LDAP client. This will make it possible for the LDAP client to connect to the master node when appropriate (add, delete, modify).

A connection check might be a good idea to catch the "master offline" scenario. This would be better than depending on cryptic error messages coming from ldap_error.