Merge pull request #53 from beheist/dev-bh-fix-header-case

BUGFIX: Fix capitalization of the "Content-Type" HTTP header

h5p.classes.php

@@ -2881,7 +2881,7 @@ class H5PCore {
    */
   private static function printJson($data, $status_code = NULL) {
     header('Cache-Control: no-cache');
-    header('Content-type: application/json; charset=utf-8');
+    header('Content-Type: application/json; charset=utf-8');
     print json_encode($data);
   }