ticketid is a string, not an int, in Uploader::sendFile()

Cast `ticketid` to a string instead of an int.

Fixes #71

Author: tacman

src/Uploader.php

@@ -135,7 +135,7 @@ protected function sendFile($filename, $params)
             $uploadResponse['originalsecret'] = (string)$xml->photoid['originalsecret'];
         }
         if (isset($xml->ticketid)) {
-            $uploadResponse['ticketid'] = (int)$xml->ticketid;
+            $uploadResponse['ticketid'] = (string)$xml->ticketid;
         }
         if (isset($xml->err)) {
             $uploadResponse['code'] = (int)$xml->err['code'];