Provide default request-format

[superstructor]

Same as #4 except for :format instead of :response-format.

If not provided when doing a POST (for example) get a 'unrecognized request format nil' exception.

[sirmspencer]

You need to use :body if you dont include a :format. The request ends up as edn, so I also stick this in. :headers {:content-type "application/edn"}