add more/better logging to help ease debugging

[stephenmathieson]

I'm currently debugging some tests that fail intermittently. The tests hit yakbak for each request and only sometimes have a matching tape. it'd be extremely useful if setting DEBUG=yakbak* when running my test suite would output more than this:

  yakbak:server req +0ms /some/path?with=some&query=strings

would you take a PR that adds a few more debug()s for things like:

• the request path
• the request hash
• if a tape was found
• if yakbak will respond to the request

[jeremyruppel]

Absolutely, I'm all for more helpful debug logs. Send a PR over and I'll ship it as soon as possible.