Beautified Wiki pages

- Better header
- Better formatting of unordered lists
- Added 'Last updated at' timestamp
- Added row-top class. Looks good enough. May use as standard all over
the website for breadcrumbs. But later.
Fixed User related and other bugs

- Fixed: User index inaccessible to bots and unauthenticated users
- Fixed: Messages page accessible to unauthenticated users
- Fixed: Unable to edit channel
- Improved security for messages
- Added cron task for site indexing