Add test data

[developeregrem]

Add some test data for initial setup with fixtures.

[developeregrem]

Fixtures added.
Run the following command to add test data for settings, reservations, invoices and templates:

php bin/console doctrine:fixtures:load --append

When you you want to add templates only:

php bin/console doctrine:fixtures:load --append --group templates

Note: app:first-run must be already executed