add empty test functions

src/test/java/de/thm/arsnova/dao/StubDatabaseDao.java

@@ -163,6 +163,12 @@ public class StubDatabaseDao implements IDatabaseDao {
 		return null;
 	}
 
+	@Override
+	public List<Session> getSessionsForUsername(String username, final int start, final int limit) {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
 	@Override
 	public List<Session> getPublicPoolSessions() {
 		// TODO Auto-generated method stub
@@ -477,6 +483,12 @@ public class StubDatabaseDao implements IDatabaseDao {
 		return null;
 	}
 
+	@Override
+	public List<Session> getVisitedSessionsForUsername(String username, final int start, final int limit) {
+		// TODO Auto-generated method stub
+		return null;
+	}
+
 	@Override
 	public void deleteAllPreparationAnswers(Session session) {
 		// TODO Auto-generated method stub