For future reference: the preflight request must return these headers:
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, HEAD, OPTIONS
Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept, Authorization, Pragma, Cache-Control
Otherwise, Safari will refuse requests made inside a service worker
reporting a preflight check fail.
When a train has a 2 minute delay, currently the scheduled time is
displayed with strikethrough and the actual time is displayed below.
This change adds a +2 after the original time to also have the relative
delay, not just the absolute one.
