Add Jest to the server application and set up a basic scaffolding for testing our API. We should use Jest as it is set up in the client Vue application as well.

We should also add a command, which runs both the API and client tests to use with CI.
The unit tests in the client are run with yarn test:unit or npm test:unit.

We can also add e2e tests to the client, as they are already set up. They are also run with yarn test:e2e or npm run test:e2e.

A basic Travis CI configuration that runs the tests would also be a great addition.

This app is too good :D

Implement the option to group Impulzes and trigger them together.
Perhaps we could also create a community based store of groups of Impulzes, where one could add a group of predefined reminders to his own list.