Implement all services in type Repository

cmd/budgeteer/main.go

@@ -22,7 +22,7 @@ func main() {
 		panic("Failed creating ID-Generator")
 	}
 
-	us := &postgres.UserService{DB: db, IDGenerator: id}
+	us := &postgres.Repository{DB: db, IDGenerator: id}
 	tv := &jwt.TokenVerifier{}
 
 	h := &http.Handler{