backstreet test pages

• slot.html — TestSlot, HTTP, port 3001
• live.html — Aviator, socket.io, port 3002
• king.html — Who Killed The King, socket.io, port 3003
• kingsolo.html — Who Killed The King solo, HTTP, port 3004

Each page talks to http://<this host>:<port>. Protocol: docs/API.md.