Remove external service dependencies when testing

[allanlasser]

By default, Feathers expects services to be available when testing. This makes testing harder and, ideally, tests should have zero external dependencies. There's a few ways we could solve this:

• perhaps the easiest is to use Node to execute the command docker-compose start postgres redis before any tests run, and execute docker-compose stop postgres redis after all tests have run.
• Another way would be to find a way to remove this dependency, either by mocking the sequelize library methods or by creating a test-specific Feathers app, rather than using the dev/prod app.