mod_audit_auth: Ignore FAST authentication events by default FAST is more like a cookie that allows linking new connections to a previous (e.g. password) authentication. Since we assume that FAST tokens are secure (not user generated) and not shareable, it reduces a lot of noise by filtering out uninteresting authentication events.

This module logs events where more than a certain amount of CPU time was
spent.

``` lua
log_cpu_threshold = 0.01 -- in seconds, so this is 10 milliseconds
```

Uses the Lua
[`os.clock()`](http://www.lua.org/manual/5.2/manual.html#pdf-os.clock)
function to estimate CPU usage.