Added scheduled scraping that removes stale datasets

.docs/api/data-service.md

...o-auth-service/listeners/target/create-event-listener.jar

...rvice/src/main/java/at/tuwien/DataServiceApplication.java

...a-service/rest-service/src/main/resources/application.yml

...java/at/tuwien/service/StorageServiceIntegrationTest.java

...ce/rest-service/src/test/resources/application.properties

...ice/services/src/main/java/at/tuwien/config/S3Config.java

...vices/src/main/java/at/tuwien/service/StorageService.java

...ain/java/at/tuwien/service/impl/StorageServiceS3Impl.java

...vices/src/main/java/at/tuwien/timer/StaleObjectTimer.java

.../tuwien/ifs/dbrepo/service/impl/StorageServiceS3Impl.java

helm/dbrepo/files/create-event-listener.jar