Having both a format query param and accept headers is confusing

[loganhuskins]

What's the default behavior supposed to be when the accept headers conflict with the format query? Which one is supposed to take precedent?

My recommendation is removing the format query param and just relying on accept headers, but if a good default can be decided on and documented I'd be happy to implement that for the project as well.

[ajzbc]

I have implemented the functionality from your pull request.