StickIt: Don't close the app when closing a JoystickWindow.

Since it now actually works to open multiple windows for different
devices, don't close the app when closing the device window.

src/tests/kits/device/stickit_BJoystick/JoystickWindow.cpp

@@ -40,7 +40,6 @@ JoystickWindow::JoystickWindow(const char *deviceName, BJoystick *stick,
 
 bool
 JoystickWindow::QuitRequested(void) {
-	be_app->PostMessage(B_QUIT_REQUESTED);
 	return true;
 }