v0.2.7 — Bug fixes: race condition, threading, CSRF TTL, session cookie

Bug fixes

• New terminals sometimes failed to connect — the page tried to open a terminal before it was ready. It now waits until the terminal is up before loading (#19)
• The server could freeze under load — one slow connection could block everything; requests are now handled in parallel (#20)
• Frequent "session expired" errors — sessions used to expire after 10 minutes; they now last 7 days, matching the login timeout (#20)
• Staying logged in across browser restarts — the session is now remembered after you close and reopen the browser