remove go-simple-db references from go-slog

- ref: https://github.com/GigaOM/legacy-pro/issues/3806
- particularly this [comment](https://github.com/GigaOM/legacy-pro/issues/3806#issuecomment-49641387)
- accompanying config: https://github.com/GigaOM/gigaom/pull/4903

Perhaps just `esc_html` the concatenated values rather than executing it on each item that is being concatenated?  Like so (maybe?):

```php
'loggly_class'    => esc_html( "{$value->tags[2]}:{$value->tags[1]}() - {$value->event->json->from}" ),
```