#63 adding missing tests

...rc/main/java/unipotsdam/gf/config/GFRocketChatConfig.java

.../java/unipotsdam/gf/core/management/user/UserService.java

...rc/main/java/unipotsdam/gf/interfaces/ICommunication.java

...f/modules/communication/service/CommunicationService.java

...oupfinding/dummy/service/DummyProjectCreationService.java

.../unipotsdam/gf/modules/groupfinding/service/GroupDAO.java

...ava/unipotsdam/gf/core/management/group/GroupDAOTest.java

...dules/communication/service/CommunicationServiceTest.java