Plan check-ins

[jheubuch]

As a user I want to plan check-ins.

If the departure time is in the future, Träwelldroid should ask whether the check-in should be made directly or be planned.
If the check-in will be planned, the user should see their planned check-ins on the app with the possibility to delete the planned check-ins.
When the departure time is reached, the user receives a push notification with which they can send the check-in.