#792 Add SkipAuthenticatedUsers parameter

[neechee]

We have a Webmaster that is always testing her site and she says that hits from her account are throwing the stats off and would like to be excluded.

We are behind a corporate firewall, so I can't do a "SkipHosts" to exclude her. It would be great if I could name one or more authenticated users to a parameter like "SkipAuthenticatedUsers=" or some such.