On a failed bind this will update krbLoginFailedCount and krbLastFailedAuth
and will potentially fail the bind altogether.
On a successful bind it will zero krbLoginFailedCount and set
krbLastSuccessfulAuth.
This will also enforce locked-out accounts.
See http://k5wiki.kerberos.org/wiki/Projects/Lockout for details on
kerberos lockout.
ticket 343
