Fixed carbon locale setting

 <?php namespace BookStack\Providers;
 
+use Carbon\Carbon;
 use Illuminate\Support\ServiceProvider;
+use Validator;
 
 class AppServiceProvider extends ServiceProvider
 {
@@ -12,12 +14,12 @@ class AppServiceProvider extends ServiceProvider
     public function boot()
     {
         // Custom validation methods
-        \Validator::extend('is_image', function($attribute, $value, $parameters, $validator) {
+        Validator::extend('is_image', function($attribute, $value, $parameters, $validator) {
             $imageMimes = ['image/png', 'image/bmp', 'image/gif', 'image/jpeg', 'image/jpg', 'image/tiff', 'image/webp'];
             return in_array($value->getMimeType(), $imageMimes);
         });
-        Carbon::setLocale(Config::get('app.locale'));
 
+        Carbon::setLocale(config('app.locale'));
     }
 
     /**