The http links for XKCD and Apple trailers don't work which gives a bad first impression when the default thing doesn't work :)
Using HTTPS they work fine.
- gives them a place to start from
- leverages existing code to import scenarios
- adds test coverage to seeds to ensure sees can run multiple times against the same db as is the case for Docker
- adds env variable to set if importing is turned on for new user
- adds env variable to point to a custom scenario for new users
