support CURLFORM_STREAM

make curl_formadd support CURLFORM_STREAM mode
Signed-off-by: babywolfh <babywolfh@gmail.com>
modify indent

modify indent
Signed-off-by: babywolfh <babywolfh@gmail.com>
Merge pull request #7 from babywolfh/master

make curl_formadd support CURLFORM_STREAM option