Improve logging on LDAP authentication test

[dthacker]

I'd like to see some better feedback and logging from the LDAP authentication test button. I've turned up the logging level to debug, bum I currently am seeing nothing in the zabbix_server.log indicating that a test has been fired, and no feedback when the test fails.
Thanks for listening!

Dave

[LenR]

I think ldap login occurs in the web client, I don't think it uses the server at all.

I suspect this, because when I forget to install the php-ldap packages, it won't work :-)