Serialize Error-typed metadata argument

[yetithefoot]

Serialize Error-typed metadata arguments more correctly to save meaningful fields.

I regularly pass an Error object as my meta object.
Code like this now will be more correctly saved to Loggly.

var err = new Error('This is error');
winston.error('Error happened', err);

[ernoaapa]

Yes please! Or some other workaround I would appreciate.

[indexzero]

Using the latest winston should fix this.