Started application of CSP headers

app/Http/Kernel.php

@@ -24,7 +24,7 @@ class Kernel extends HttpKernel
      */
     protected $middlewareGroups = [
         'web' => [
-            \BookStack\Http\Middleware\ControlIframeSecurity::class,
+            \BookStack\Http\Middleware\ApplyCspRules::class,
             \BookStack\Http\Middleware\EncryptCookies::class,
             \Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
             \Illuminate\Session\Middleware\StartSession::class,