For LdapLogin, make ou configurable in the xml
Created by: JieNanMAXIV
Minor change, just to make the ou configurable (e.x., maxivusers<\ldapou>). In details, it's for ldapconnection.simple_bind method: if ou is defined, bind_str will be "uid=xxx,ou=xxx,dc=xx,dc=xx", otherwise it is "uid=xxx,dc=xx,dc=xx".