Add the possibility for the user cleanup to also look for the disabled/inactive users in ldap and delete them

I propose to add two more configuration properties. One will be the ldap attribute that is used to signal that an user is active or not. The other one is the value the attribute will have when the user  is disabled. In active directory,  for example, an user is disabled/inactive when the `userAccountControl` attribute is set to `514`. 

When the clean up code runs, it will also check that the ldap user does not have that key-value pair in the attribute list.

This improvement would serve for this particular Active Directory application issue https://github.com/xwikisas/application-activedirectory/issues/50 .