Returning HTTP 200 instead of HTTP 500

```
See https://code.google.com/p/opencaching-api/issues/detail?id=20#c26.

In case of PHP fatal error, OCPL is returning error description along with the 
HTTP 200 status. Should be HTTP 500, with NO error description.
```

Original issue reported on code.google.com by `rygielski` on 18 Dec 2013 at 8:04
