PyPump.request() should be able to get any type of content #132

Current version of PyPump.request() returns response.json(), which means it can only be used for requests where the server will return json data.

We should rewrite it so that it can return all types of content (the full response object?), and let the caller of PyPump.request() decide what to do with it.

This would f.ex let us download media files from https://example.com/uploads/ with pump.request(imgobject.original.url) instead of having to do something weird like requests.get(imgobject.original.url, auth=pump.setup_oauth_client())