Minor cleanup and documentation improvements.•••- Only show a generic failure message to the user upon oper failure
due to not having a secure connection or matching cert. fingerprint.
- Update the comment about oper:fingerprint as it can be a space
separated list of fingerprints and not just one.
- Improve a few code comments and formatting.
Don't override a different Displayed Host with the rDNS.•••If the dnsbl module is set to mark with a vHost, it can finish before
the hostname resolution finishes. This is especially the case when
the result is already cached.
Resolves #1770.