net: give better error messages

Add address and/or port to errors where applicable for better reporting.

See #7005
Bugger. The only way I can think to deal with this is to manually manipulate the `.stack` string. Something like this:
```javascript
var stackArray = err.stack.split('\n');
stackArray.shift();
stackArray.unshift(message);
err.stack = stackArray.join('\n');
err.message = message;
```
You'll still have to assign the `.message` property as well. Or else inspecting the object will show the wrong output in the form of `[Error: message]`.