Investigate possibility to support stop id related GTFS-RT service alerts

[teemu8655]

check google/transit#219

[mjaakko]

Needs specification:

• How long before scheduled departure time should the service alert be shown? (to avoid having too many alerts in the UI)
• What information should be included in the service alert title and description? (e.g. route name (U, I, R,...), destination, departure time from first station, departure time from the station where the platform change is, new platform number, original platform number?)

[Slaveriot]

More detailed spesification:

• Service alert should be generated 15 minutes before departure from stop where track change occured. Validy should last until scheduled departure from that station + 1min.
• Alerts shouldn´t be generated to stops that are terminus of the route aka last stop of route. (no purpose to customers)

Information content
Lähijuna "routeShortName" "headsign" kello "scheduledDeparture from stop where change occured" lähtee raiteelta "new departure track" Paikka: " Stop name"

Information example
Lähijuna L Siuntio via Kirkkonummi kello 18:18 lähtee raiteelta 8. Paikka: Pasila
Närtåg L Siuntio via Kirkkonummi kl. 18:18 avgår från spår 8. Plats: Pasila
Commuter train L Siuntio via Kirkkonummi at 18:18 leaves from track 8 Location: Pasila

Metainformation also included:
"trip": gtfsId":id of unique trip"
"stop": gtfsId":id of stop where vehicle on static gtfs-data departs aka normal stop"
Severity: "info"

-JNa

[teemu8655]

Not relevant at this point. Added trips solution is better option.