Even more fixes

Even more fixes in the background and small tweaks to the UI.

Latest changes:

• Added a Terms of Service page (can be found in the footer)
• Updated the Error page slightly and fixed authentication issues
• Upgraded the site to redirect to HTTPS automatically
• Changed the way some backend pages load (site should be even faster now)
• Fixed the issue with the changelog RSS feed (can be found at /changelog/feed.xml)
• Fixed a bug that prevented user signups
• Fixed a bug that didnt mark invites as used