Create migration to add NB and SB endpoint booleans to Stations table.
Perform migration. Edit red line seeds to include new endpoint boolean data.
Edit main controller to use new station endpoint attributes for trip validity. Bug fix in seeds file before seeding the DB.
Edit seeds file to include new nb_endpoint and sb_endpoint data for all stations.
Add Trip model with valid? method to test validity of trip and migrate. Edit main_controller to use Trip.valid?