net: give better error messages

Add address and/or port to errors where applicable for better reporting.

See joyent/node#7005 and #16 
You can write this as:

```javascript
server.on('error', common.mustCall(function(e) {
  // ...
});
```

Can you tell why you aren't testing the exception object for expected properties here?

Aside, tests should generally be quiet when successful.