checker: fix start and stop

checker/main.go

@@ -36,10 +36,12 @@ func main() {
 	defer ticker.Stop()
 
 	// Launch checker
+	studentsChecker()
+loop:
 	for {
 		select {
 		case <-interrupt:
-			break
+			break loop
 		case <-ticker.C:
 			studentsChecker()
 		}