application: properly quit application

Fixes destruction process. Calling g_application_quit skip the reference
decreasing process of GApplication and that resulted in a bunch of
_finalize methods not being called. By removing the windows GApplication
finalize properly.

src/gcal-application.c

@@ -329,7 +329,12 @@ gcal_application_quit (GSimpleAction *simple,
                        GVariant      *parameter,
                        gpointer       user_data)
 {
-  g_application_quit (G_APPLICATION (user_data));
+  GcalApplicationPrivate *priv;
+
+  priv =
+    gcal_application_get_instance_private (GCAL_APPLICATION (user_data));
+
+  gtk_widget_destroy (priv->window);
 }
 
 /* Public API */