Revert "UOCL-285: payment screen hanging (#42)"

This reverts commit 0c6b84dd5f.

src/main/java/com/unicenta/pos/payment/JPaymentSelect.java

@@ -749,7 +749,7 @@ public abstract class JPaymentSelect extends javax.swing.JDialog
             };
 
             //worker.execute();
-            customExecutor.submit(worker);
+            customExecutor.execute(worker);
         }
         catch (Exception ex) {
             System.out.println(ex.getMessage());