When on, users get shown a maintenance page, except if you have the VIEW_MAINTENANCE permission. The admin area works either way and you get shown a small 'maintenance mode' watermark in the bottom right corner.
- Moved initOrGetGroup and updateMetadataGroup into own MetadataController.php becauseits really big and cluttered the PlayerController.php
- Added Challenges and pciked challenges for the characters
- Added that when the game sends us an update for the Character metadata, it automatically creates unknown challenges in the database and sets the picked challenges for this characterData
