0.7.0.0: Auto-shutdown and auto-closing connections on JWT expiration

• The server postgres-websockets will shutdown when the listener database connection is closed, this allows for external process supervisors to restart the service on database failures.
• Middleware interface now requires a parameter IO UTCTime prividing a function that will produce the system time.
• Send close connection once the JWT token expires (if channel is open with a token using the exp claim).