Merge branch 'feature/grafana' into 'dev'

.docker/docker-compose.yml

.docs/api/dashboard-service.md

.docs/api/metric-db.md

.docs/concepts/database.md

.docs/concepts/monitoring.md

.docs/images/screenshots/grafana3.png

.docs/images/screenshots/grafana4.png

.docs/images/screenshots/grafana5.png

.gitlab-ci.yml

dbrepo-auth-service/docker-entrypoint.sh

dbrepo-dashboard-service/Dockerfile

dbrepo-dashboard-service/dashboards/rabbitmq.json

dbrepo-dashboard-service/dashboards/system.json

dbrepo-dashboard-service/grafana.ini

dbrepo-dashboard-service/ldap.toml

...o-dashboard-service/provisioning/dashboards/provider.yaml

...ashboard-service/provisioning/datasources/prometheus.yaml

dbrepo-data-db/sidecar/Dockerfile

dbrepo-data-service/pom.xml

...ice/src/main/java/at/tuwien/endpoints/SubsetEndpoint.java