log event.id when available

[mmcgahan]

This PR is partly for discussion, but it's a feature that we would like to use - adding the request.id in the request event log from good-console. This makes it much easier to connect the request.log calls that correspond to a particular request rather than the 'anonymous' logs that would otherwise be printed.

Let me know what you think - we can definitely write our own Good stream/reporter, but I figure this might be generally useful.

Downsides

1. more verbose logging (but not much more verbose)
2. changing the logging output might break custom log parsers that are tuned to the existing good-console output
3. the current formatting in this PR doesn't 'tag' the event.id with anything other than parens, which might make it less grepable

Thoughts?

[arb]

Get the tests all passing again, and this looks fine to me.

[mmcgahan]

All set, thanks.