don't send a lower case content-type header when forwarding

lib/http_forward.js

@@ -39,7 +39,7 @@ module.exports = function(dest, req, res, cb) {
   });
 
   if (req.headers['content-type']) {
-    preq.setHeader('content-type', req.headers['content-type']);
+    preq.setHeader('Content-Type', req.headers['content-type']);
   }
 
   // forward cookies