You can now send any EntityEnclosingRequest with POST fields or POST
files and cURL will handle creating bodies
* Lots of cleanup to CurlHandle::factory and RequestFactory::createRequest
* POST requests using a custom entity body are now treated exactly like PUT
requests but with a custom cURL method. This means that the redirect
behavior of POST requests with custom bodies will not be the same as POST
requests that use POST fields or files (the latter is only used when
emulating a form POST in the browser).
* Closes #266