Handle CAA requests in Seer and prefix logs with `tau`

[samyfodil]

• using autocert to generate SSL Certificate using lets's encrypt hits seer for CAA of tau. before granting any cerificate. Only manifest if the fqdn has a sub-domain. example: enterprise.starships.ws -> CAA for tau.enterprise.starships.ws is queried and need not to return an error.
• fixing this I needed to look at debug logs and without tau. it was hard to filter. So adding that.