Allmost finished stationboard

TODO:
- Using real data from the phone (currently impossible because I'm not able to get the original JSON keys out of the Tuple on the Pebble)
- Arival time
- maybe som animation?
- Highlight when a train is delayed
- performance optimisation (on update, the watchface freezes for about 4-5 seconds)
- also, there is somewhere a memory leak I could not find...