* stop treating it as class property
* refactor to consolidate logic into one big 'if' statement
(for easier removal when the config option gets removed in the future)
* make deprecation warning for 'ldap_use_ssl' more urgent
* raise error if conflicting settings 'ldap_security' = "starttls" and
'ldap_use_ssl' = True are set together
* if not set, infer 'ldap_security' = "tls" from 'ldap_use_ssl' = True,
logging a warning for the admin to update the config
7eb0c66512