test: added AbstractSourceAdapterTest for handling most adapter tests
test: CsvSourceAdapterTest now also tests all protocols
filter: added XmlSourceAdapter
test: removed junit annotations from server classes

Leftovers ...
filter: added InvalidDocumentFilter for removing non objects from json
test: added CamperParkingBremen for xml source testing
test: added InvalidDocumentFilterTest
monitoring: added DbHealthCheck for checking db state at runtime