Login system

[gruelingpine185]

Description

Added more routes: `login/` and `signup/`. These routes will act as the gate between the user, the game, and other related items. ## Changes

• New files added to views/ for login/ and signup/ routes
• Added Colors for buttons/input UI elements. (Some already exist, but they are theme specific rather than universal)
• Moved all .html files in public/ to views/ (removes extension in url)
• Linked 404 page so that it get rendered on invalid route

  Solves

• Closes #109

[devkennyy]

• [ ] Add email verification step
• [ ] Add checks / requirements for passwords, emails and usernames
• [ ] Profanity filter
• [ ] Redirect to index after login
• [ ] Display username if signed in (beside navbar icon)
• [ ] Make login/signup pages use themes