setup integration tests for api

[danielschleindlsperger]

inspiration: https://github.com/marblejs/example

• [x] setup tests with database
• [x] setup builders/factory for testing
• [x] setup auth flow for testing

[danielschleindlsperger]

first integration tests added in e22a3c1d7d697c848e00d243affb5f2c897ae3cf and d321e60070fdf558e599e0a9d30bedf0cd75e361

[danielschleindlsperger]

implemented: e8b4fe50a95f0698d266c18f79bbdf9b4b7f3714