added MatchIdNotFoundException #25

sth-backend/src/main/java/hdm/mi/sthbackend/exeptions/MatchIdNotFoundException.java

+package hdm.mi.sthbackend.exeptions;
+
+import java.util.UUID;
+
+public class MatchIdNotFoundException extends Exception{
+
+    public MatchIdNotFoundException(UUID matchId){
+        super(String.format("MatchID %s not found", matchId.toString()));
+    }
+}