#40 refactor: refactor management class and move functions into separate DAOs

...c/main/java/unipotsdam/gf/config/GFApplicationBinder.java

...c/main/java/unipotsdam/gf/core/management/Management.java

...in/java/unipotsdam/gf/core/management/ManagementImpl.java

...in/java/unipotsdam/gf/core/management/group/GroupDAO.java

...ava/unipotsdam/gf/core/management/project/ProjectDAO.java

...ava/unipotsdam/gf/core/management/user/HiddenUserTag.java

...rc/main/java/unipotsdam/gf/core/management/user/Menu.java

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

...main/java/unipotsdam/gf/core/management/user/UserDAO.java

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

...ava/unipotsdam/gf/core/management/util/ResultSetUtil.java

...rc/main/java/unipotsdam/gf/core/states/PhasesService.java

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

...rc/test/java/unipotsdam/gf/interfaces/ManagementTest.java