Remove Expect header

Remove the `Expect` header which is [not handled](https://blog.pilif.me/2007/02/02/the-return-of-except-100-continue/) by many hosts (including the API gateway apparently).

Author: jweisman

proxy.php

@@ -137,6 +137,7 @@
 
 // let the request begin
 $ch = curl_init($request_url);
+array_push($request_headers, 'Expect:'); // Many hosts don't support 100-Expect
 curl_setopt($ch, CURLOPT_HTTPHEADER, $request_headers);   // (re-)send headers
 curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);     // return response
 curl_setopt($ch, CURLOPT_HEADER, true);       // enabled response headers