Maintenance mode from CONFIG file

Hi, I made a small fix in the code, in case someone wants to do maintenance on the live environment and needs to disable login/editing. The setting is done via the CONFIG file, so it doesn’t need to change the localization.

CONFIG.PHP

return [
'maintenance' => 'Oops! Under maintenance.'
];

This setting is checked

  • when logging in, it just hides the login form
  • when checking the role, function isAllowed
  • displaying a 401 error, where information about system maintenance is added

Resolves #206