static image support for other formats

- update response object handling within the static image interface
- exposed support for svg, pdf, and jpeg
We may want to consider using requests definitions to check status codes:
https://github.com/kennethreitz/requests/blob/master/requests/status_codes.py

In this case, if we are *only* checking for `ok`, so it would look like this:
```python
if res.status_code == requests.codes.ok:
    # do stuff
```

Maybe not here, but the codes (201) 'created' and (202) 'accepted' might be used elsewhere in our APIs and could be returned from our servers.