Http error code

@danfruehauf I will buy you a beer if this doesn't work!

I tested with:

```
$ curl -w "\n\n%{http_code}\n\n" "http://localhost:8081/geoserver/aodn/wms?service=WMS&version=1.1.0&request=GetMap&layers=aodn:coastal_watch_locationsasdf&styles=&bbox=138.468,-38.542,153.627,-19.148&width=400&height=51&srs=EPSG:4326&format=application/openlayers"
```

(obviously against the non-static geoserver, but anyway, same deal - I hope).