Header Enhancements (#4541)

* Header Enhancements

* Doc Updates for HaveHttpHeader

Author: bnpatel1990

src/Codeception/Lib/Connector/Guzzle.php

@@ -216,7 +216,7 @@ protected function extractHeaders(BrowserKitRequest $request)
 
         $contentHeaders = ['Content-Length' => true, 'Content-Md5' => true, 'Content-Type' => true];
         foreach ($server as $header => $val) {
-            $header = implode('-', array_map('ucfirst', explode('-', strtolower(str_replace('_', '-', $header)))));
+            $header = html_entity_decode(implode('-', array_map('ucfirst', explode('-', strtolower(str_replace('_', '-', $header))))), ENT_NOQUOTES);
             if (strpos($header, 'Http-') === 0) {
                 $headers[substr($header, 5)] = $val;
             } elseif (isset($contentHeaders[$header])) {