Add postBody and setRequestBody functions to POST some data in a test.
Second attempt to write a good postBody and setRequestBody.
Get post function back without overwriting content
Small spacing fix
Remove unused comment
Use GADTs for static guarantee you use right type of post data.
Revert "Use GADTs for static guarantee you use right type of post data."

This reverts commit 3655af11d3be0fdece443706bbc96ea9c52b458d.
Add error-reporting when trying to add file or post-param after binary content is set.
Refactor a bit to make pattern matching happy and makeMultipart only work on multipart data.
Merge pull request #578 from k-bx/master

Add postBody and setRequestBody functions to POST some data in a test.