[Bro] Adding policies & bro.cfg

[Vern Paxson]

[sorry for the delay in following up on this]

> There is an entry in the bro.cfg file for the 'start policy'. I am guessing 
> that this is not 'local.site.bro' because that already lives in $BROHOME/etc 
> and apparently gets called automatically.  What typically goes in the start 
> policy?

The convention we've used is that there's a file hostname.domain.tld.bro
(e.g., watcher.lbl.gov.bro) which corresponds to the specific config that's
running on the host hostname.domain.tld.  This will for example load a
specific set of anlayzers and redef "interfaces" to match the particular
hardware used by the host.

		Vern