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

Also, we should replace this old `config()` pattern with the more current one. `go-loggly` has an example, I think. 

Key points:

1. Don't set it in `_construct()`
1. Don't call it as a setter, ever (let it fetch its own data)