Implement option to opt out of console report

By default, a report is sent to the console (“Parsed Items: #” for `.parse()`; “File saved” for `.write()`). You can pass a second argument `false` to bypass this behavior. Like so:
```javascript
var json = csv.parse('path/to/file', false);
csv.write('path/to/file', false);
```

This patch doesn’t break expected behavior. If no second argument is passed, module behaves as before (reports to the console as usual).