Do not pass timelimit and deref settings to ldap_search. These values
should be set globally via ldap_set_option() instead (as we do for
deref).

adLDAP renamed the ad_username and ad_password to admin_username
admin_password recently. this makes our backend recognize the old
settings

again)

canDo getUsers to false when unavailable

This reverts commit ba09710a.

Conflicts:
	lib/plugins/authad/lang/de/settings.php

de/de-informal: config plugin - Clean up the TOC in the configuration page / No need to add "Konfiguration" or "Plugin" to every element if the heading tells you that.

Without this unable to access AD info. Also allows SSO.

Wihtout this, unable to fetch any AD info.. also allows SSO.