Add explicit logging when NIP-05 verification requests fail

[danielemery]

Like reported in #130 and #147 I was also having trouble diagnosing why NIP-05 requests were failing.

In my case it was:

1. Because my server was returning a 404 when the name query string was being provided (I only tested it without a query string)
2. Because my server wasn't returning a content-length header

I debugged these issues by running this forked version with extra-logging version locally and pointing a client at it.

I thought I would raise a PR with the extra logging in case it makes sense to upstream.