Merge "registration: Generalize CoreVersionChecker to VersionChecker"

diff --cc autoload.php
index 9dba6cd,91f7700..76613e7
--- 1/autoload.php
--- 2/autoload.php
+++ b/autoload.php
@@@ -1524,8 -1522,8 +1523,9 @@@ $wgAutoloadLocalClasses = 
        'UzConverter' => __DIR__ . '/languages/classes/LanguageUz.php',
        'VFormHTMLForm' => __DIR__ . '/includes/htmlform/VFormHTMLForm.php',
        'ValidateRegistrationFile' => __DIR__ . '/maintenance/validateRegistrationFile.php',
+       'VersionChecker' => __DIR__ . '/includes/registration/VersionChecker.php',
        'ViewAction' => __DIR__ . '/includes/actions/ViewAction.php',
 +      'ViewCLI' => __DIR__ . '/maintenance/view.php',
        'VirtualRESTService' => __DIR__ . '/includes/libs/virtualrest/VirtualRESTService.php',
        'VirtualRESTServiceClient' => __DIR__ . '/includes/libs/virtualrest/VirtualRESTServiceClient.php',
        'WANObjectCache' => __DIR__ . '/includes/libs/objectcache/WANObjectCache.php',