Work around nasty bug in some http libraries that prevents POSTing.

Both Peclhttp and Curl libraries default to sending the Expect: 100-Continue
header when Posting data over a certain size. This makes it impossible to
POST to a server that does not support this header and correctly returns a
417 response code. The libraries do not attempt a fallback, nor do they
make it clear that this is the default.

framework/Core/lib/Horde/Core/Factory/HttpClient.php

@@ -28,7 +28,7 @@ public function create(array $opts = array())
                 }
             }
         }
-
+        $opts['request.headers'] = array_merge($opts['request.headers'], array('Expect' => ''));
         return new Horde_Http_Client(array_merge($client_opts, $opts));
     }