Allow both anonymous and authorized bind
Allow both anonymous and authorized bind

OpenLDAP by default allows anonymous search, however Active Directory does not allow anonymous search (as smdion pointed out). This file should allow for *both* options.
* Added a flag `$anonbind` and a conditional to set `$preauth` based on `$anonbind` and the user set within `$binddn` and `$bindpass` to allow either method to be used.
QMXTech/Codiad-LDAPExternalAuth