Added Multipart from creator
added PATCH and multipart post

Selectable chunkedEncoding on the multipart
setting NO will mean the body gets streamed to disk and uploaded from
there
setting YES means the request will be streamed dynamically, but no
Content-Size will be sent (also if you are using an application server
that doesn’t support chunked encoding you will see problems)

coalesced code into encodeBody function (for POST/PATCH/PUT)

Deal with crash when no response body but json content type set

Dumped PodSpec